Another computer won’t start. (Complicated)

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Hi everyone,

One day a few weeks ago the grandkids turned off the computer I set up for them and it would not turn on again in the morning. Followed the power up to the Mobo. The Mobo LEDs are lit up, but absolutely nothing happens when the on switch is pushed. Everything else looks good. Power supply is Corsair HX 750 about one year old, not the most likely candidate for failure especially since the LEDs on the Mobo are on. I decided the on/off switch was probably bad so I replaced that. Didn’t help. My son-law, a computer software engineer say is must be the Mobo. I took a Mobo and CPU that was working in another computer and put it in the inoperable computer. Boy was I disappointed, it still will not turn on. Both Mobos are ASUS Sabertooth 990FXs. CPU is FX8350.

I am at a loss as to what to do next.

Help!

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When you swapped the mobo and CPU did you also use their HDD as well or just leave the original in ?

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When you swapped the mobo and CPU did you also use their HDD as well or just leave the original in ?

Same boot SSD was used. Computer does not get to POST much less to the disk.

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There is a manual here – just to confirm you plugged everything in properly.

http://dlcdnet.asus.com/pub/ASUS/mb/SocketAM3+/SABERTOOTH_990FX_GEN3_R2.0/E8041_SABERTOOTH_990FX_GEN3_R2.pdf

Are you using the original processor or did the replacement board have one already fitted? Check the DIMMS. If you have more than one, try one at a time. Remove any PCI cards. If you have a graphics card, try using the onboard chip instead. If it still doesn’t work, try changing the PSU.

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Can you access the BIOS/UEFI?

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Can you access the BIOS/UEFI?

No. See above answers as well.

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I replaced the Mobo with the processor and DIMMs complete as a unit from a case where they worked fine. The only PCI card is the graphics card which was the one from the older PC. Can a graphics card prevent the board from even starting up to POST or any other signs of life? (No onboard GPU). I don’ have a spare PSU, but as I said it is fairly new and is providing power to the Mobo at some level as the LEDs are glowing on the board. This is why I am so confused.

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Can you access the BIOS/EUFI?

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Not being able to access the BIOS/UEFI means either a motherboard issue, or your monitor is dead.
Just because it worked fine previously means little to me. I’ve seen motherboard behaviors where it worked well enough, then would fail to POST.
Take your system back to bare bones and keep trying. You may need to look into resetting the BIOS/UEFI, so look through your documentation.

If you have on the board graphics, remove the card and attempt to POST again. (Remember: Bare bones)

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Not being able to access the BIOS/UEFI means either a motherboard issue, or your monitor is dead.
Just because it worked fine previously means little to me. I’ve seen motherboard behaviors where it worked well enough, then would fail to POST.
Take your system back to bare bones and keep trying. You may need to look into resetting the BIOS/UEFI, so look through your documentation.

If you have on the board graphics, remove the card and attempt to POST again. (Remember: Bare bones)

Hi Clint, thanks for your attention. I am fairly familiar with single Windows PC having been using them for at least 40 years, but I am still confused by this. (I used this breakdown as an opportunity to get a new mobo for my main computer. I did install the new mobo, then installed and restored WIN10 on that PC and it was working the first time I closed the case, so I have the basic skills.) For all practical purposes everything which resides on the grandkid’s transplanted motherboard was in verified working condition before installing on the old PC, yet I have the same problem as the old board. The only thing that seems left to do is check the monitor, based on your comments. Can you explain how the monitor would stop the booting up of the mobo from very start. No activity at all is apparent on the mobo, such as the LEDs that show the booting status. (Also. no on-board graphics). It still seems like it is not getting a start signal. Is there anyway to test that? (I changed the CMOS battery before installing on the old computer).

Thanks again.

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Clarification on the LEDs. After reading my posts it is a little confusing as I said the LED were on and were not coming on. There is a green LED that shows that power is coming to the Mobo. The other LEDs are red and show that the board is doing its start-up proceedure. These red ones do not come on and no other hints of activity are noticable either.

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My thought was there could have been a problem with the original HDD and as you had swapped the other bits, then give the replaced mobo a try with its own HDD/SSD.

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My thought was there could have been a problem with the original HDD and as you had swapped the other bits, then give the replaced mobo a try with its own HDD/SSD.

Thanks for the thought. I do not think it is the drives as the mobo does not come on enough to even look for any drives, much less access them. Am I misunderstanding something here on the boot up process?

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You have a Boot sector on the HDD so if the disk was goosed then it wouldn’t boot up – give it a try as I’ve suggested.

Also open the DVD player drawer prior to booting as I’ve come across where that can hang a boot.

You can open the drawer with something like a straightened paper clip or darning needle by waggling it in the pin hole in the drawer.

Have you also tried booting up with an install disk ?

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Can you explain how the monitor would stop the booting up of the mobo from very start.

It wouldn’t, if the monitor failed then you’d just get a black screen, but you’d still hear the fans kick in and see LED indicator lights on the board.

The hard drive has nothing to do with being able to access BIOS. NO POST means game over. The drive is not the issue.

You don’t mention whether fans are running or their RPM?

You’ll need to go through your documentation to find out what your on board LED error codes are and how to reset BIOS.
Take the system to bare bones and:
1. Bare bones with only one memory stick at a time. (sometimes bad RAM will take your entire system down, but usually you will have beep errors or LED error codes.
2. Reset BIOS by moving jumper pins, do this with the bare minimum of components needed, no drive attached. (may need to persist with several attempts-take your time)
3. Swap out the PSU or use a voltage tester, the green LED means your getting standby power, but not necessarily operating power.
4. Switch out the graphics card or test it’s functionality in another system.

It’s most likely your motherboard that is the fault since that is the newest component, then memory, PSU, GPU (not in order).
Processor unlikely, but if you seated it yourself then re-seat it.

What LED’s on the board are on? (red is not good-look them up]

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PSU. Best bet. Swap a known working one in.

If that is the cause it is still under warranty.

You can do a couple of crap tests: Paperclip test, then if it starts up you can test with a VOM if you have one. But since it is not under load only failure to hit the expected voltages on the lines is a fail.

https://community.newegg.com/eggxpert/computer_hardware/f/135081/t/98567.aspx

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PSU. Best bet. Swap a known working one in.

If that is the cause it is still under warranty.

You can do a couple of crap tests: Paperclip test, then if it starts up you can test with a VOM if you have one. But since it is not under load only failure to hit the expected voltages on the lines is a fail.

https://community.newegg.com/eggxpert/computer_hardware/f/135081/t/98567.aspx

Hi FN, Wish I had known about the paper clip test a few weeks ago. Just today I found it on the Corsair site. The PSU did fail the paperclip test and a new one is on the way already. Crossing my fingers that this is the solution. It makes sense.

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Well, it was the PSU. I was fooled by the standby power. Won’t happen again!

Thanks for all the suggestions.

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