Making connections between computers and monitors

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ISSUE 19.16 • 2022-04-18 HARDWARE By Ben Myers With four different standards for video ports and cables, as well as some “mini” ports, it can be downr
[See the full post at: Making connections between computers and monitors]

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ibe98765, MHCLV941, WSGeo, oldfry, lmacri, roy.l.dixon, wdburt1, fisher75, Cybertooth, SupremeLaW, SueW

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Great information.  Please do the same for wireless connection to monitor/TV.  I understand there is one type that works without having an internet connection to the TV and other types that require internet connection on both the laptop and TV.

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rc primak

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Help!  I do not have a collection of adapters to test wifi broadcasting to my TV.  ;>)

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Nice writeup – but not to forget about the various DVI versions (DVI-D, DVI-I, DVI-DL, etc), which make it really painful to find the proper solution if there is one at all.

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ibe98765, Charlie, Cybertooth, SupremeLaW, wavy, rc primak

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Yes, I confess to giving DVI short shrift, subliminally hoping it might go away.  As real estate for connectors on laptops gets smaller, DVI has disappeared as a connector on modern laptops, supplanted by a combination of miniDP, DisplayPort and HDMI.  DVI is still present on some newer desktop and tower video cards.

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The close-up photos of the various connectors were especially helpful. Thank you for the article. Now a question: You state that the HDMI audio signal to the monitor can be disabled using Windows Device Manager. Great, but my look at the monitor entry in Device Manager tells me about the driver, etc., but nothing about how to disable the audio. If possible, can you give a more detailed explanation as to how to do this? Any guidance is appreciated.

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SupremeLaW, wavy, rc primak

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In Windows 10 or 11, try right-clicking the Speaker Icon in the Tray Area and select Sound Properties or Sound Devices. Then in the Settings Panels, select each device listed, and Enable or Disable them as needed. Finally, go to the Sounds Settings Panel (old-style Control Panel page) and test using any of the Windows Sounds. There is also a Speaker Test for Left and Right Speakers in the Sound Devices Settings Panel.

I switch frequently between Thunderbolt-3 headset and 3,5 mm Headphone Jack setups, among others, and my monitor is HDMI with sound capabilities (actually, an old Toshiba HDTV). So I am constantly doing sound setup changes for Zoom Meetings (no speaker feedback tolerated!) and everyday listening with Speakers (daytime) or Headphones (Night-time).

I also have to do similar sound setup gymnastics under Linux. Pulse Audio is a real trip to set up and change settings, and to test for Zoom meetings and video sharing.

Anyone doing Apple/Mac/iPad?

Then there are Wireless schemes. That’s a whole other can of worms! I even have Wireless HDMI transceivers! Chromecast, various MS Miracast and TiVo Stream devices figure into my wireless video and sound devices setups. I don’t use infrared, but I do use Bluetooth in several iterations.

-- rc primak

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SupremeLaW, F A Kramer, wavy

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Fortunately, there is little need any more to resort to VGA-BNC.  Plus audio, of course.

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SupremeLaW

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It looks like RC Primak nailed it with a right click and disable.  I had one client with an older nVidia card with HDMI, DVI and VGA connectors and an nVidia driver set.  The card and driver together did not understand that the HDMI was not in use, and nVidia’s audio driver got installed to confuse things.  Disable this driver in Device Manager, and Windows no longer has a choice of audio output, so it is forced to use the one audio driver remaining.

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rc primak

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G-r-e-a-t article, especially with the pictures!

I’ll add one note: When I’m confused about cables, connectors, or converters, of _any_ type, I go to CablesToGo.com ( https://www.cablestogo.com/ ). Their cables may be a little more expensive than some others, but they are generally of highest quality. And you can find good photos and explanations of all the different connectors.

I have no affiliation with this company, except that I’m a very happy customer.

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ibe98765, WSGeo, roy.l.dixon, SupremeLaW, F A Kramer, rc primak

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Plus One for Cables To Go.

-- rc primak

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SupremeLaW

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Make that plus two! I also have patronized Cables To Go for years and had excellent service from them.

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SupremeLaW

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Another way to ID unknown connectors is if you have an Android phone with Google Lens on it (or you can download it if it isn’t on the phone), take a photo and then use Lens to ID it.

This also works for most anything unknown, such as plants or flowers on a hike.

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MHCLV941

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Great write up. I was a technician when my organization transitioned from single to dual displays as a standard. There really are so many different cabling combinations and adapters needed to make dual monitors happen with a fleet of devices manufactured at different times.  One thing we found useful that I didn’t see mentioned is the advantages of Displayport 1.2 In many cases, we found it was easier and more cost effective to use Multi-Stream Transport to daisy chain monitors with DisplayPort 1.2 ports rather than fiddle with adapters all the time. Also imagine that you could write a whole article on the overlapping topic of Audio connections. AV cables carrying audio only makes that more complicated. With the new normal of WFH, and the mix of laptops, docking stations, computers, remote desktops, headsets, phones, we have daily disruptions to business with users troubleshooting Speaker and Microphone audio, and this is true within our IT department. Our end users suffer even more.

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SupremeLaW, wavy

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And to top it off, there was Component Video. For professional equipement, this kind of signal was mostly transferred over coax with BNC connectors at one end and a VGA connector at the other end. Back in the day, we had to use those kind of cables to connect the high end videocard to a large 21″ CRT.

Component Video can use a LOT of different connectors – probably enough to fill a chapter on it’s own…

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SupremeLaW

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Many thanks, Ben:  this is very helpful.

Please forgive me for not reading all of the text:  you may have mentioned this little problem already.

In your Figure 2, focus on the DVI pin-out diagram, with particular attention to C1, C2, C3 and C4.

Now compare the corresponding DVI female pins in Figures 10 and 11.  Figure 12 shows the male version.

Now compare Figures 16, 17 and 18.

Whenever C1-to-C4 females are MISSING, the corresponding male pins will prevent standard DVI connectors from mating.  We ran into this problem with a refurbished HP workstation:  the integrated DVI connector on the rear I/O panel lacks C1-to-C4 female sockets.

Fortunately, in our spare parts we just happened to have a compatible cable, but all of our DVI-to-VGA adapters have C1-to-C4 pins, so they just do NOT work!

 

Many thanks, again, for all the helpful photos.

 

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I should also mention the extra layer of complexity that occurs if a setup requires a KVM switch (keyboard / video / mouse).

Our backup storage servers still use PS/2 connectors, and our KVM switches still require VGA connectors for video.

Happily, we found a quality DP-to-VGA adapter from StarTech that works fine to connect our newer HP workstations to our KVM switch.

Bottom Line:  when shopping for a compatible KVM switch, pay very close attention to all of the hardware you plan to connect to that KVM switch.  When in doubt, contact the manufacturer for expert guidance.

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Will Fastie, wdburt1, Cybertooth

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Another seemingly trivial concern is the condition of the mechanical connections.  See Figure 10, in particular.

On both sides of VGA and DVI connections, there are 5mm hexagonal nuts with integrated female threads.

We always dab some 3-in-1 oil on a cotton swab and carefully apply that oil to those threads.  In the long run, this helps to prevent “fusing” that can occur slowly over time.

Also, over-tightening the matching threaded males can cause another problem when they must be disconnected:  the entire hex nut disconnects from its housing.

Over time, we have learned to use “muscle memory” to pre-tighten the hex nuts in place, and then to apply less torque when mating the male threads after applying oil.

On occasion, a DVI-to-VGA adapter simply wears out, and the male threads on hex nuts strip their plastic housings:  in that event, a little lock-tite can often fix that nagging problem.

Lastly, a machinist taught me this trick, decades ago:  when connecting machine screws, start by turning counter-clockwise until the matching threads “snap” into place.  Often, there is no sound, but that “snap” is something that can be felt as a vibration in your hand.

The last time I stripped the threads on a machine screw must have been 20 years ago!

Hope this helps.

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ibe98765, Charlie, Cybertooth

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The documentation for my LG monitor warns “Using a DVI to HDMI or DidplayPort to HDMI adapter may cause compatibility issues.” What sorts of issues can result?

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SupremeLaW

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Connecting cable types cease to be a concern when an All-In-One (AIO) PC/Mac is purchased.

I’ve been using AIO’s for over 10 years, love ’em, the only cable needed is their power cord.

To be fair the AIO’s do have input and output ports, typically USB3’s and HDMI ports for input and output. However for the most part they are purely optional for usage.

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SupremeLaW

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I have never used an AIO.  You mentioned “HDMI ports for input and output”.

I can see how an HDMI output port could run a second monitor.

But, how would an “HDMI input port” function on an AIO?  Perhaps to connect peripherals like a blu-ray player?

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I found the above at Newegg:

ASUS Zen AiO 24 – 23.8″ FHD Touchscreen – AMD Ryzen 7 5700U – 16 GB DDR4 – 512 GB SSD – Win 10 Home – Kensington Lock – Wireless Keyboard & Mouse (M5401WUA-DS704T)

Zen AiO 24 features an HDMI-in port, so it’s easy to hook up to a laptop, mobile device, game console, or even a set-top TV box for an amazing big-screen experience. It boasts an array of ports for connecting all your peripherals, and an HDMI-out port to connect to an external display.

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My only reservation about AIOs comes from repairing or upgrading them.  Many are extremely difficult to open up to get at the area needing attention.  Worst situation I ever encountered was replacing a dead hard drive with an SSD in an Apple Mac AIO with brilliant beautiful hi-res screen.  iFixit bailed me out with special tools and two-sided adhesive strips to re-attach the screen.  I would not wish that repair on anybody, but I might possibly be more adept at it, if there ever is a next time.

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SupremeLaW, Cybertooth

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The article begins with “In the best of all possible worlds, we would all want to buy a computer and a monitor at the same time.”

I beg to differ. The statement does not hold true if the user wants to work with the best monitor, and perhaps keep doing so while computers come and go. (The same is true with keyboards and mice.)

The”best” monitor is not merely an esthetic issue. For certain uses, some monitors are better proportioned than others. The widescreen (1.77:1) format currently used was adopted because movies were in widescreen and the manufacturers could cut cost by ditching 16:10 monitors and standardizing on one type of panel. It wasn’t about productivity. There are even those in areas like graphic arts who still prefer the old 4:3 or 1.33:1 format.

Also, manufacturers’ abandonment of CCFL monitors and shift to LED over a decade ago may have saved them money and reduced energy use (and heat), but it came at the expense of increased blue light and risk of associated retinal damage, as the US government warned at the time. So now we have manufacturers touting ways to reduce blue light by adding a yellow filter.  (So much for color accuracy.)  Personally, my eyes cannot stand looking at an LED screen all day long.

If you have invested some trial-and-error in this, as I have, then you end up with a box full of adapters and hybrid cables such as those shown in this valuable article. Fortunately, if all you really need is DVI, the newer types of connection are backwards compatible in the sense that a hybrid cable or adapter will pass through the DVI signal without conversion.

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SupremeLaW

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Good article, Ben! I’ve struggled with this issue since my first IBM-clone in 1986 with green text CRT monitor. I saw one mention of wi-fi, maybe in jest. Is a wi-fi connection currently available or a possibility for the future?

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SupremeLaW

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I’m quite far from having any real expertise to answer your question.  My only experience that even comes close is the cabling I got working with an older Viewsonic 27″ monitor.  I connected a USB 2.0 port on a simple laptop computer, to one of the USB 2.0 ports on the rear of this monitor.  That connection now allows me to plug USB thumb drives into the other USB ports on that monitor.  Thus, without knowing the internal details, it appears that this Viewsonic monitor contains a simple USB hub.  By inference, I assume the other empty USB port on that monitor could accept a WiFi dongle, of which there are many options to choose from.  The Viewsonic model number is VX2739wm .

 

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roy.l.dixon

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In the wiring diagram above:

“USB Up” is cabled to a USB 2.0 port on my laptop (i.e. “Up” = to the “host”)

“USB Down” on the left side of that diagram works AOK with my USB thumb drive

“USB Down” immediately to the right of “USB Up” is currently empty

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roy.l.dixon

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There is an error in the wiring diagram above (“RTFM” = Read The Fine Manual 🙂

The cable from “Audio In” should connect to the green audio jack on the PC’s rear I/O panel.

I’ve attached a better illustration from Viewsonic’s archives:  it clearly labels “Audio Out” for headphones, speakers etc.

By leaving the “Audio Out” jack empty, “Audio In” drives the integrated speakers (which are not very good;  that’s why we have never used them).

(It’s a bit rough for beginners when factory documentation is NOT correct.)

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Cybertooth

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error in wiring diagram above is fixed in the attached

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Some older Dell monitors also can function as a simple 2-port USB hub also connected to the computer with an ubiquitous USB cable, the kind usually packaged with most USB printers.  The USB port at arm’s length is often more convenient to use than USB on the tower computer down on the floor.

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SupremeLaW

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Re:  the kind usually packaged with most USB printers

Attached is a photo showing both Type-A and Type-B connectors.

Type-B is annotated in red.

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Some really really fast short haul wifi would make a wifi-connected monitor practical, except for gaming where frames per second rules the day. I have not yet seen a way to connect a monitor to a computer, but since I hoard computer gadgets, widgets and connectors, I’ll probably but a wifi monitor kit when it comes available.

 

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roy.l.dixon, SupremeLaW

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for comparison purposes, the attached is the wiring diagram for the Viewsonic model VX2757-mhd, which is a newer model that we purchased after the model above

it does not have a USB hub or any USB connectors, however

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Thanks again, Ben! We have a huge screen monitor at our church which works well for slides and videos with WIFI to HDMI, but I had no idea if it could replace an HDMI cable nearby. It used a 100′ ethernet cable before, but I never knew the interface at both ends.

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For a standard desktop or laptop setup, if you have at least one digital video connection (DVI, HDMI, DisplayPort, or a variation of one of those) on the computer, or if you have USB-C, you can get some sort of adapter to make it connect up with whatever digital video connection is on your monitor. Therefore, although the best thing is to get the same type of video port on your monitor and your computer, it isn’t a big deal if you don’t have that.

Something interesting I discovered with my previous laptop: There were two video ports on the laptop: HDMI and Mini-DisplayPort. The monitor had an HDMI connection, but not a DisplayPort connection, so I used an HDMI cable to make the connection. At some point, for some reason I got a Mini-DisplayPort to HDMI adapter and connected the cable to the Mini-DisplayPort connection on the laptop – when I did that, I got better video quality than when I went straight HDMI on both ends! The only thing I could figure as to why Mini-DisplayPort to HDMI produced better video quality than straight HDMI was that the laptop was using an older version of HDMI, because I have never seen that situation on any other computer. Point is, try different video connections to see what gives you the best video quality.

Also, although VGA is low-resolution, I like it when there is a VGA port on the computer, because VGA is a good emergency backup plan for video. VGA is not too good in terms of video quality, so I wouldn’t want to use it for daily use; but it may be all you have in a pinch. This would be helpful mainly in a corporate environment, where they may have an old VGA monitor stashed away somewhere, and someone could temporarily connect the VGA monitor and keep working until they could replace their regular monitor.

Group "L" (Linux Mint)
with Windows 8.1 running in a VM

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I have not run a monitor with a VGA connection at a resolution higher than 1920×1080, the resolution of my regular monitor on my test bench.  That’s a pretty high resolution.  But compared to any of the digital monitor connections, VGA appears fuzzier because it is.

I am aware of anomalies with HDMI, too.  For example, one of my clients has a pretty recent high end laptop that travels back and forth from home to work.  At work, he uses a monitor with DisplayPort, and it is flawless.  At home, he uses an HDMI connection and he claims it is somewhat glitchy.  I keep telling him to use DisplayPort at home, but he is a very busy executive who won’t allow anyone into his home office man cave.  If he would take photos of the DisplayPort on his laptop, probably miniDP, I could surely help him with the right cable or a converter cable, but he is a busy man.  Quality and revision level of the HDMI cable could also be the problem.

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DisplayPort has a max bandwidth of 32.4 Gbps and can support up to 4K at 120Hz with 10 bit color.

HDMI 1.4 (available starting 2010) has a max bandwidth of 10.2 Gbps and can display up to 4K at 24Hz with 8 bit color.

HDMI 2.0 (available starting 2014) has a max bandwidth of 18 Gbps and can display up to 4K at 60Hz with 10 bit color.

HDMI 2.1 (available starting 2018) has a max bandwidth of 48 Gbps and can display up to 4K at 144Hz or 8K at 30Hz with 10 bit color + HDR.

Notes:

HDMI is “backwards compatible” but only supports the resolution/speed/color depth of the slowest port in the connection.

HDMI cables should be certified for 2.1 to ensure you get the higher specs (i.e. older 2.0 era cables may not support 2.1’s higher bandwidth.)

HDMI 2.1 only started appearing on laptops in early 2021 and “usually” only those with a discrete graphics GPU (i.e. Nvidia or AMD.)

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teuhasn2, oldfry, roy.l.dixon

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Your post reminded me that I was still using an HDMI cable between my video card and my monitor, even though both my video card and monitor have [full-size] DisplayPorts and MiniDisplayPorts, and since as you say the resolution would be better, I should switch to a DisplayPort cable. Well the only one I had was a DP-to-miniDP cable that was bundled with either monitor or video card, I forget which. I websearched the obvious question, and interestingly, miniDP resolution and speed is considered as good as [full-size] DP, so I hooked up the cable and it worked great.

Except that Windows kept trying after each PC reboot to send the audio to my monitor speakers, and I don’t use those; I use the motherboard audio to go to an amp and my better speakers. The fix, as suggested above, is to go into Device Manager and Disable the driver for monitor speaker audio.

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My own monitor also has both DP & miniDP ports but my graphics card only had DP ports.

Thankfully the monitor came with a DP-to-miniDP cable and, as you discovered, the only difference between the full size and mini DP is the actual “physical size” of the connector. They both use the same number of pins and thus provide the same video specs.

BTW, even though my particular monitor doesn’t have speakers, I also had to disable the driver for the monitor speakers because it did include a headphone jack that Windows keep trying to use as its default sound source instead of the motherboard audio.

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teuhasn2

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Similar to what I have seen, the combination of monitor, video card and its drivers does not have the necessary intelligence and logic to detect that a DisplayPort-connected device does not have any audio capability.  This seems to be fairly common.  The video device itself should be able to present the video card with information as to whether or not it handles audio.  This seems to be an area that hardware manufacturers and video-with-audio driver installers need to manage better.

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Just another Forum Poster, Cybertooth

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In 2008, the computer industry responded with DisplayPort, a standard defined by the computer-industry standards group now known as simply VESA, formerly the Video Electronic Standards Association. Figure 4 shows the full-sized DisplayPort pinout.

The progression from VGA to DVI to HDMI seems a reasonable progression, but why does DisplayPort exist? It seems as if VESA simply worked itself into a snit because it didn’t come with HDMI and created DisplayPort just for spite.

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Cybertooth

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Intel and Apple did the first version of DisplayPort.  With possible slight variations, Apple calls it ThunderBolt, and now some non-Apple laptop manufacturers have taken to the ThunderBolt nomenclature.  Thunderbolt in its latest iteration can do more than simply video and audio, with some multiplexing of signals possible along a ThunderBolt link, and this may be the best rationale for ThunderBolt.  The group of TV and TV accessory manufacturers were quite narrow in their vision in the design of HDMI.

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MHCLV941, oldfry

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ibe98765 wrote:

Another way to ID unknown connectors is if you have an Android phone with Google Lens on it (or you can download it if it isn’t on the phone), take a photo and then use Lens to ID it.

This also works for most anything unknown, such as plants or flowers on a hike.

Does this work for color-coded connectors? USB type-A connectors come in a number of different colors which are related to the connector’s specs and capabilities.

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