120mm fan based CPU cooler would be better than a 92mm fan based cooler. [NAME] did a nice video installing a Cooler Master 120mm Hyper TX3 EVO into a G5 5090 with a similar chassis. No cutting required and no backplate removal....he removed the plastic pins and replaced them with M3 bolts. Fit was tight under the side panel....needs to be verified that this would fit into the XPS 8940.  It should. This one fits as well without cutting or drilling,  but is 92mm fan based:  Cooler Master Hyper T2   The fact that Dell created a location in the top front of the XPS 8940 chassis for a 3.5" HDD is great.  Was wasted space in the G5.     The Corsair H60 AIO CPU liquid cooler can mount in that front location and would have been great for CPU cooling.  Move that 3.5" HDD mounted in the front location up to that top bracket and install the AIO.  However, in their infinite wisdom they proceeded to block all the airflow through the upper part of the XPS 8940 front bezel.  The G5 front bezel had some nice slats for airflow....the XPS 8940 is a solid upper front bezel......no airflow in that location.     No liquid cooling folks unless you want to modify that rear 80mm fan location for a 120 mm fan on that H60 cooler.    All you can do is update that rear exhaust fan to a 92mm fan and add an intake fan in that lower front position to help with airflow and update the CPU air cooler.  The Asetek 645LT is possible in the XPS 8940 case, but a 92mm liquid cooler is for SFF cases where there is no option for a 120mm AIO unit.  Temps aren't that great....ithe 92mm fan and small radiator are limiting and temps are similar to the 120mm air coolers.
Hello there I would greatly appreciate any help to find a new/better 3rd party cooler for my XPS 8940. It came with the thin and small stock cooler and is overheating the whole time. I got a i9-10900 processor with 128 GB of RAM and I need this computer to generate some GIS layers. These jobs take 2-4 hrs every time and I can see that the processor is throttling or C° 97+ all the time. I tried the Noctua 15S but the problem is there is no space for the bracket under the motherboard. The stock fan screws directly into the chassis from above. Thank you very much
XPS 8940, Better 3rd party cooler