XPS 8940, Nvidia Resizable BAR, activation

From this, it looks like only an Asus motherboard is currently compatible.

Even if the XPS 8940 is compatible, you're also going to need an RTX 30 series video card and a new NVidia driver too.

And since NVidia just officially announced Resizable Bar yesterday, it's probably going to take a while before you will see this...

@lbmn  - You may be interested in comments posted by Dell-Chris M (forum Community Manager) about Resizable BAR in the Alienware Forum here.

I updated my Dell OEM RTX 3070 comes with my XPS 8940 long times ago and it works, but of course the motherboard BIOS still need to be updated to make it work. I used the VBIOS from this thread: RTX 3090/3080/3070/3060 Ti VBIOS - Dell Community I thought it's likely the same GPU for both Alienware and XPS so I bit the bullet and it certainly didn't brick my card. Use at your own risk, YMMV as it's for Alienware. At the time of this post no XPS VBIOS is provided yet. 

As of the motherboard BIOS, it was literally released a few days ago and yes it supports Resizable BAR: Dell XPS 8940 System BIOS version 2.2.0 It took me quite a few tries to update as it simply ignore the update at boot time. I have to use flash drive to update from the boot menu instead. The new BIOS adds an option to turn on Resizable BAR in performance section. Then you can check if Resizable BAR is enabled in NVIDIA Control Panel. 

However the side effect is that my extra HP EX900 on a adapter card in PCIE x4 slot doesn't work anymore and will hang at boot. Have to remove it to make it boot. I tried other NVMe SSDs (SK Hynix PC611 and Crucial P1) and they simply disappear from the system (both Windows and BIOS). Dell really should put two NVMe slots on the motherboard for expansion. I'm pretty sure it's a stupid compatible issue, just like the very limited RAM support for this motherboard. And because of the chipset choice, you don't get to use PCIe 4.0 devices, too, such as the graphics card it comes with

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@x-magic wrote:

XPS 8940 

As of the motherboard BIOS, it was literally released a few days ago and yes it supports Resizable BAR: Dell XPS 8940 System BIOS version 2.2.0 

However the side effect is that:

a. my extra HP EX900 on a adapter card in PCIE x4 slot doesn't work anymore and will hang at boot. Have to remove it to make it boot.

b. I tried other NVMe SSDs (SK Hynix PC611 and Crucial P1) and they simply disappear from the system (both Windows and BIOS). 

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Sounds like your PCIe-slots are fairly broken now.

@x-magic  You may be able to use BIOS Recovery and the BIOS Downgrade option (Table 11) in BIOS on the XPS 8940 to go back to the previous version so your slots may work again, but you'll have to give up Resizable Bar...

See https://www.dell.com/community/XPS-Desktops/XPS-8940-does-NOT-support-dual-NVMe-SSD-drive/m-p/8087371/highlight/true#M66267

It's not my slots broken, it's Dell's BIOS which is broken.