Precision T7920 Workstation Resizable Bar Support

Question

We recently acquired a Precision 7920 workstation with dual Xeon processors. We want to install a pair of Intel Arc Pro B70 graphics cards for some AI lab work. However, try as we might, we can't get the machine to boot when we install both, or even one of these. I have memory map IO above 4GB enabled in BIOS. Has anyone else encountered this, and hopefully resolved it? I'd really appreciate any guidance you may be able to offer. This is an awesome, albeit slightly older, workhorse of a machine and we really want to make this work.

robarola · Accepted Answer

Thanks all for you comments and suggestions, but none of them even get close to the real problem here. I actually have this solved, and I'm at this moment running 2 Intel Arc Pro B70s along with an older AMD video card to drive my dual monitors. This turns out to be a super simple problem with a rather complex solution that Dell could fix (and SHOULD FIX) with a simple BIOS update. Here's the issue: Dell has a setting built into their BIOS code that allows configuring the 7920s non-volatile RAM to allow the system to address the GPUs on boot up. Dell has consciously chosen to hide this setting. It literally DOES NOT EXIST in any BIOS binary for the 7920. The only way to make this work - and I seriously mean this - THE ONLY WAY TO MAKE THIS WORK IS TO CHANGE THE SETTING YOURSELF BY ACCESSING THE NVRAM DIRECTLY AND ALTERING THE SETTING YOURSELF. You haven't missed the setting, because Dell hides it from you by not even showing the setting in BIOS at all, despite the fact that the setting exists in the code behind the scenes. I posted about this problem on Github. There, a brilliant individual did many hours of hard research and experimentation until he found the setting and figured out how to change it. He provides perfect step-by-step guidance and suggestions for making it work. I followed those and bingo, I'm doing what Dell, et al have essentially told me was impossible. Running 64 total Gbs of VRAM via 2 GPUs, with a separate video card to run monitors. I just can't imagine why they wouldn't update the BIOS to simply make visible a setting that's already in the BIOS code so we could all do this with a tick box instead of the gyrations I went through. Could be they don't want to extend the life of these machines?

(edited)

robarola · Accepted Answer

Today I installed a third Intel Arc Pro B70 card in one of our T7920 machines. That's right - 3 cards! It runs them perfectly and I now have 96Gb of VRAM for an AI project. I'm also running 2 Intel Arc Pro B70s in a 5820 workstation. The fix seemed a bit challenging at first, but turned out to be profoundly simply and straightforward. Anybody with even basic skills can do this, and breathe new life into your older 7920 and 5820 era workstations. I created 2 guides - 1 for the 5820 and 1 for the T7920 workstations. This platform doesn't allow me to attach them, but you can find both here: https://github.com/xCuri0/ReBarUEFI/discussions/331  - look for the posts by GezelligLLC. Forget all the discussions about modding or hacking your BIOS, or of loading some custom BIOS. As for the folks posting lazy AI generated responses that don't even represent reality.. ooh boy. Those folks are barking up the wrong tree and I believe you're at real risk of harming or even bricking your machine The ONLY real, safe, 100% effective way to do this is to simply increase the setting that already exists in BIOS, but which is not exposed in the BIOS config screen. If Dell did choose to expose it, you'd simply tick a box or type in a value and PRESTO! you'd accomplish exactly what I present in the guides. But Dell hasn't updated their BIOS and from what I'm reading elsewhere, they have no intention of doing so. So all of us owners of these machines are at a crossroad - do we scrap these awesome older machines, or do we make a super simple change and use them to do valuable, exciting work again. We made a simple choice, spent 30 minutes executing on it and are now rocking and rolling. You'll see on the github post a chap who even scripted the process to make it fully automated. Full disclosure here: I did not use a script (he hadn't created it when I updated our machine). Nonetheless it shows just how easy this is, and would be for Dell to do for us by simply exposing the setting in BIOS... hint, hint.

Tesla1856 · Answer

Try with just one.

Be sure Power-Supply is big-enough and all the video-card's PCIe-Power cables are connected.

Disable Secureboot.

Still not working? ... remove coin-battery and do a CMOS reset.

robarola · Answer

@Tesla1856​ - thanks so much for the advice. I have a 1400 watt power supply. I tried with only 1 of the b70's. Definitely had 8-pin PCIe power cable connected. I disabled secure boot. None of those worked. Our machine just boots to the BIOS screen - never makes it to OS boot loader. However, I have not tried removing the cmos battery and / or doing a cmos reset. Will give that a try next. Has that worked for you?

Tesla1856 · Answer

@robarola​ , 1. Our machine just boots to the BIOS screen - never makes it to OS boot loader. 2. However, I have not tried removing the cmos battery and / or doing a cmos reset. Will give that a try next. Has that worked for you? 1. If it's Posting, I wonder why the OS is not loading ... weird. 2. Well, yeah ... recovering from a SecureBoot Violation (red box) once. Also read it helps others to get a clean Post after swapping video card (they were getting no video-no Post).

robarola · Answer

@Tesla1856​ Unfortunately, the cmos battery / cmos reset didn't help either. This 7920 just boots directly to bios screen. So frustrating. Given the huge number of these machines out there, I would hope that Dell might weigh in at some point

bradthetechnut · Answer

The 7920 was released in 2017. I suggest replacing the size 2032 battery with a new one and reset BIOS via blue jumper method. I've had success with this when my 3620 would no longer boot and it gave me freezes and BSOD.

It usually doesn't do any good to put the same battery back in place unless it was tested.

robarola · Answer

@bradthetechnut​ Thanks a bunch for the suggestion - changed the battery with a fresh one, reset bios. No change. Boots straight to bios. I'm running Linux, so no BSOD, but I never get as far as the OS bootloader.

Tesla1856 · Answer

@robarola​ ,   This 7920 just boots directly to bios screen.  Is it fully Posting and stopping at a working BIOS and/or UEFI-Environment screen? Or it really just locked-up with one of the BIOS screens showing (and keyboard is non-responsive)?

robarola · Answer

@Tesla1856​ - yes, the machine boots into fully accessible / working / responsive BIOS. I've spent hours experimenting with various BIOS settings and rebooting over and over again in hopes a change might work. But...nooooo.

bradthetechnut · Answer

@robarola​  A few ideas, some you may have tried already. BIOS set to RAID, Secure Boot on.  Toggle Secure Boot off if it doesn't boot.  If still no boot, try AHCI and toggle Secure Boot. Does BIOS show any bootable devices and what is showing?  If you repeatedly press F12 upon powering on, does it let you go to the Boot & Diagnostics menu? If you have a Windows boot drive installed, boot devices in BIOS should show Windows Boot Manager at the top of the list.

bradthetechnut · Answer

@robarola​  If you make it to the Boot & Diagnostics menu, 2 things:  1. Try running diagnostics.  2. If boot device shows, try booting from it.

Tesla1856 · Answer

@robarola​ , @Tesla1856​ - yes, the machine boots into fully accessible / working / responsive BIOS. I've spent hours experimenting with various BIOS settings and rebooting over and over again in hopes a change might work. But...nooooo.  Well, Intel-Graphics PCIe card, Intel Chipset Motherboard, Intel CPU ... It's all Intel so something should work. It's a puzzle.   Mark the cards and treat them like one might be bad.   Always try SecureBoot OFF first, but them quickly try with it on before you change hardware config again.   As @bradthetechnut says ... If you can get to ePSA Diags, run them.   If F12 works, boot a flash drive (like Windows or Ubuntu installer).

robarola · Answer

@Tesla1856​ and @bradthetechnut . I really appreciate all your suggestions. I cannot get to the diagnostics screen via F12. The machine boots straight into BIOS. I cannot boot from a USB drive. I am literally locked into BIOS. I tried the secure boot options - no good. This is not an issue with my boot drive. If I remove the Intel card, the machine boots perfectly into Linux. My boot drive shows in BIOS. The problem is that I can't get past the POST process / BIOS to even get to the OS bootloader. This seems to be a BIOS setting - or a BIOS setting that just doesn't exist on the 7920. This Intel Arc Pro B70 has 32GB of VRAM and requires Resizable BAR support, which on some machines is as simple as enabling Memory Map above 4GB. Clearly not on this machine. I have Memory Map IO above 4GB enabled. That was one of the first things I confirmed. I've heard some users say there may be 'hidden' BIOS settings to make this work, but I honestly don't even know what that means. I have tried every setting in BIOS that I can think of. I see others experiencing problems with this exact configuration and was hoping to entice Dell to actually weigh in, rather than just ignoring the 7920 owners who are trying to extend the life of these really great machines. I'm hopeful that you or others may have more options to try, but my hope is definitely dwindling. I've tried installing only 1 intel card, then the other, then both - same result.

Tesla1856 · Answer

@robarola​ ,   1. I cannot get to the diagnostics screen via F12. The machine boots straight into BIOS. 2. This Intel Arc Pro B70 has 32GB of VRAM and requires Resizable BAR support, 3. I've heard some users say there may be 'hidden' BIOS settings to make this work, but I honestly don't even know what that means.  1. This is not common, and points to some deep-rooted hardware compatibility problem.   2. That is a fairly extreme and important system hardware requirement. I think now you know why it doesn't work. 3. That just means the BIOS screens should be set to 'Expert' or whatever they call it on that machine.

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Precision T7920 Workstation Resizable Bar Support

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