I was unlucky enough to go through the same problem you are going through. I tried EVERYTHING that was suggested here, to no avail. I ended up removing the graphics card and I haven't had an issue since.

@Y4L​ That's interesting. I will keep that in mind. Thanks.

Well, I finally had time today to do the clean windows install. We'll see how it goes now.

So I was on the phone with a Dell Support Agent, because I have TWO XPS 8940s also freezing (One AMD, One NVIDIA). I also am at my wits end. However, there is a new BIOS update, 2.19.1, that apparently addresses bug fixes. I installed it, and it still appears to be freezing for me, but worth a shot to install it on your machine.

@akess505, @LGordonG,

The ODDS on ANY BIOS alone fixing the Nvidia freeze/lock-ups are SLIM to NONE.

Seriously, depending on the problem, DDU can help (for Nvidia) but it is not a guarantee. There is probably no sure fire single answer for the Nvidia problem.

I've seen a myriad of answers here, and some claim to have had luck ONLY using the Dell POSTED drivers (usually not the most recent Nvidia versions though). Others say the non-Game Ready ones work OK. Other use a BIOS setting to turn off the Turbo Boost.

I on the other hand found a combination of BIOS version (V2.13.1, yes I am way back level) and the Nvidia Control Panel 3D power setting to Max. Power. I use the latest Nvidia Game Ready Driver, and do a CLEAN INSTALL on every new driver release (and check the Nvidia Control Panel to make sure it did not change the Power Setting, yes, it has done it occasionally). I install the new driver via GeForce when it finds a new driver.

Don't want to do any major tweaks or they do not work for you, disable the video card and use the on-board HD750 Intel video card built into the 8940... that will not cause a problem other than possible reduce display capability.

Me, until takes 'ownership' of the Nvidia problem and declares it fixed in the latest BIOS (problem started in Jan. 2021 with the release of BIOS V2.4.0) in the README for the new BIOS, I'll wait, or at least watch the forums if uses declared it fixed with the new BIOS.

So, I suggest at a minimum at this time, change the Nvidia Control Panel 3D Power setting and see if that helps?

@ispalteng ​ My 8940 is running 2.19.1 without issues, I did notice one thing with the new motherboard that Dell stuck in the system it is Pci Express 4.0, not Pci Express 3 on the GPU port. 

I realized this after dumping out all my old screenshots and PC pictures when I was tinkering with the 8940 a lot. My old board was PCI Express Gen 3 x16 on the GPU now it shows PCI Express Gen 4 16x though the Nvidia system info panel. 

I do know every board I had that was a dell board that ways GEN 3 PCI express had issues this does not. 

My XPS 8940 is running an RTX 4070, 64 GB DDR 4 3200 (2933) MHz memory, and the i7 11700. The only thing I changed was the cooler Noctua D12L in Dual Fan config. and the GPU. It was fine with the RTX 3060 ti as well after the MB change.  

I double-checked it with hw info, the replacement board is a Gen 4 chipset 

 Also, the motherboard through sys info is a Dell Inc. with Baseboard A00  I checked for anything on the motherboard that would say Foxconn or anything nothing, so it looks like an actual generic intel board customized for Dell. 

@JamieLinux​ 

One one of the thoughts and reasoning for the Max. Power as too many times the lock-ups occurred whenever the system was 'idle' and you moved the mouse, or were trying to wake it up from sleep. Thoughts immediately were the video card was 'sleeping' and somehow missed the 'wake-up call'. That or something overwrote the video buffer address (would not think that was possible). Tinkering with Max. Power, i.e., the card never reduced power or went to sleep.

Of course, each card IS different too, and some might not have that problem. Also, the DEFAULT 3D setting for power differs from card model to model. The Default being Adaptive power on my RTX2060. Others have Optimal I think or another default, but Max. power is no a default on any card.

Here is what the Control Panel says about my possible Power Settings:

So the assumption is/was if the card is always ON, that takes the card sleeping out of the equation.

I will say this, Dell and/or FoxConn or even Intel with the Management Engine changes that went to BIOS V2.4.0, none of them have either taken ownership of the problem(s) or even acknowledges it and/or appear to be working them.

If it works for you, great. I'm stable here, and until I know it is truly fixed without needing other tweaks, I guess I have to sit here.

I learned from BIOS V2.4.0 and later BIOS versions, in some case either you couldn't go back in version as the problem remained, or if it was working OK, the next BIOS broke it again.

I know I'm gambling with not going to the latest, and I will miss some Security fixes, but so far, that doesn't seem to be a problem (and I take back-ups twice a week).

My Motherboard is:

BaseBoard Manufacturer Dell Inc.
BaseBoard Product 0427JK
BaseBoard Version A00

According to the FAQ posted, these are the 'possible' 8940 motherboards:

Motherboards =
KV3RP Foxconn 02012PQ00-600-G, Released July 9, 2020
2W4W1 Foxconn 02012TA00-600-G, Released December 1, 2020, Brazil only
F1H92 Foxconn 02012YJ00-600-G, Released March 15, 2021, Brazil only
427JK Foxconn 02012VY00-600-G, Released March 15, 2021
K3CM7 Foxconn ??, Released July 14, 2021

The ?? on the last one sort of makes me think that it might not be Foxconn's? That was the one that Dell sent to be put into my 8940, and it would not boot? 2 of them even...

Possible there are newer or even 'beta' ones that Dell got/has? Don't know, but surprised they upped some components/chips?

I am quite sure you know how to determine the PCIe speed, and the 'standard' 8940 does not support 4.0. Of interest though is this link here, https://www.dell.com/community/en/conversations/xps-desktops/xps-8940-not-supporting-pcie-gen-4/647f94ddf4ccf8a8de7434a3 where this was discussed and explained to someone who thought they were at 4.0... (Spoiler, the card IS).

I can't see anything that points to me what speed mine is other than the 8940 Spec's per se. Mind sharing how you saw it? What Motherboard are you on? I'd be real angry if it is fixed in the motherboard though.