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  • More on undervolting (I didn’t realize it was so big)

    Posted on Ascaris Comment on the AskWoody Lounge

    Home Forums AskWoody support PC hardware More on undervolting (I didn’t realize it was so big)

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      • #2286622 Reply

        This is a follow-up post to my previous one on the topic.

        Even though I did succeed eventually in rolling back my firmware to 1.11 on my Dell G3, the next to newest version that did not block undervolting, something still didn’t sit right. I had seen that there was a way to find the address of the bit that determines whether undervolting is possible in the UEFI, and if I were to make use of that, I could have the most up to date version of the firmware (with the other security fixes that don’t carry a heavy penalty like losing the ability to undervolt). I tried the method described by one individual, but there was quite evidently a step missing between extracting a bit of the firmware and his display of the parsed data.

        Some people in the thread had mentioned that with some Dells at least, all one has to do to revert the disabling of undervolting is to go to the UEFI settings and trigger the factory reset. Apparently Dell overlooked that when it comes to disabling the undervolting (or maybe they overlooked it on purpose to give us a way of doing it while still enforcing security measures officially?), but I had dismissed that, as it was one of the first things that I tried, and it did not work… until I realized that I’d performed the reset to “BIOS” defaults, not the factory reset (the two had been conflated in my mind).

        I’d have to go back to the non-undervolt firmware to test it. While a part of me said, “If it ain’t broke, don’t fix it,” the bigger part of me said, “You never know ’till you try.” I have the modified firmware file that will revert the firmware, so I can go back again if needed.

        I flashed the newer firmware and did the factory reset this time, and sure enough, undervolting does work.

        I am still disappointed that Dell would give me an option to enable firmware downgrades, and even though I had it checked, it refused to allow the downgrade. I’m also disappointed that Dell would summarily disable an important feature in the service of “security,” which is a common theme in computing these days. Security is an important thing, but it’s not the only thing. We’ve seen it manifest in all kinds of performance-destroying “fixes” for threats that are unlikely to ever manifest, and the pressure we all have seen to install any and all patches the moment they are released, a topic that Woody has addressed in the past.

        In this case, Dell and the other OEMs could include an undervolting interface within the UEFI settings. On component desktop motherboards (motherboards sold by themselves to be used by an integrator to build a PC) usually do have these features enabled, and my Asus P8P67 Deluxe board is no exception. I can adjust all kinds of nitty-gritty overclocking features and tweak everything from the UEFI, so there’s no reason to ever fool around with such things from within the OS.

        That’s not usually the case with laptops (gaming or otherwise). There are a lot of things I can change in my Dell G3’s settings, but things like undervolting, overclocking, fan profiles, etc., are not among them. If I could undervolt and change the power limits from within the UEFI, I’d be okay with not having that ability from the OS. I’d prefer it, actually, as the potential security threats are not imaginary, although the one in question (Plundervolt) is about SGX, which I have disabled anyway.

        If Dell did deliberately “give” us the factory reset option as a backdoor into undervolting, I’d give them points for that, but there is no way to know if they did it intentionally or if they simply overlooked it.

        In the process of leaning about all of this, I discovered that the prevalence of undervolting to improve the thermal performance of laptops is much greater than I thought.  When an anonymous poster called gaming laptops a sham (or something to that effect), I disagreed… s/he was not wrong that a robust cooling solution in a small laptop body is not possible, but it’s also not true to say that they simply don’t work. Even without undervolting, I’ve run games for hours and had good frame rates on my G3, and while it was hot, it worked.  If you want the ability to game on the go, gaming laptops will deliver, even if they do have drawbacks compared to desktops (and they surely do).

        It’s not just gaming laptops that people undervolt, though. Laptops with powerful CPUs and integrated graphics can still throttle quite a lot, and they can benefit from undervolting too. Dell’s XPS series uses discrete GPUs, but they’re not sold as gaming machines.

        Undervolting, I’ve found, is used across the board by all kinds of laptop owners. It reduces heat output, increasing performance, and it also can noticeably improve battery life. Some OEMs, like Apple and Razer, are said to use undervolting from the factory to improve the thermal and battery performance of their units. They can still have things improved, more than likely, as the factory undervolting is not precisely tailored to each individual unit’s capabilities like the PC owner would do, but the improvement would be less than with a non-undervolted model like my Dell.

        FWIW, I have a fairly high undervolt on my G3. Undervolts are done in increments of millivolts, and I’ve undervolted the GPU and CPU by -150 mv, generally thought to be near the top end of a reasonable undervolt.  I’ve tried more than -150, but I had stability issues. At -150, I’ve done some of the same testing that I did when overclocking the desktop, specifically running Prime95 for hours on end with no issues.  A kernel panic (the Linux or Unix version of a BSOD), lockup, or spontaneous reboot indicates instability, meaning that the undervolt in one of the areas is too high.

        The commonality of undervolting would seem to suggest that laptop OEMs should give users the tools to make use of it. Prior to Plundervolt, they generally did not do anything about it, neither giving options to do it from the UEFI settings nor blocking it from being done at the application level, but post Plundervolt, most have taken the quick and easy way of just blocking it at the application level and leaving it at that.  They’ve done this at the request of Intel, which seems to be a bit short-sighted, given that AMD’s mobile offerings apparently perform considerably better on power-per-watt than Intel, which is certainly a pleasant surprise. Undervolting is not possible on AMDs, but from what I gather, it’s not really necessary either.

        I’ll very definitely be considering this whole situation next time I am in the market for a high-performance laptop. Before I bought the G3, I didn’t know much about undervolting… but now that I have seen what a difference it can make, it’s a tool I want to have, in the Intel world at least.  As I’ve learned, there are a ton of us with Intel laptops that think that way, and Intel summarily telling OEMs to disable a feature that makes Intel CPUs far more appealing than the suddenly resurgent AMD could bite them in the rump.

        Group "L" (Fedora 32 Linux w/ KDE Plasma).

        • This topic was modified 1 month, 2 weeks ago by Ascaris.
        2 users thanked author for this post.
      • #2286632 Reply
        AskWoody MVP

        I’ve had a little dabble with undervolting with my Xeon/i3 Ivybridge ITX desktops, primarily to reduce noise and secondarily to reduce power consumption. I’m still happy on W7 and some carefully chosen hardware; B-series ‘board with the i3, Z-series with the Xeon (reduces Intel telemetry traffic) but I’m still really narked that MS dropped (or gave an alt. that was almost impossible to follow) XP Hardware Profiles:

        They were quite easy for an experienced user to set up and tune the Windows install from (almost) the outset. Then bring on the hardware tuning/undervolting, please!

        1 user thanked author for this post.
        • #2286664 Reply

          I remember seeing the hardware profiles and thinking that they were there if I needed, but I never thought that I needed them. Hadn’t actually noticed that they’d been removed!


          Group "L" (Fedora 32 Linux w/ KDE Plasma).

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