The  XPS 8940 service manual makes no mention of removing or installing a "VRM heat sink". It only mentions a voltage regulator heat sink, which is required for all 10th Gen CPUs, above an i3.

If there actually is a VRM heat sink, you can try contacting Dell Spare Parts at 1-800-357-3355. Have Service Tag available...

The VRM only comes with specific models of the XPS 8940, I believe it is the K-series processors that include the heatsink. You can call the spare parts number or chat with customer support and you can purchase the heatsink for $5 with free shipping. The part number is 612F7.

Here is a picture of the heatsink (don't buy this it's $24) https://www.amazon.com/Deal4GO-Regulator-HeatSink-Replacement-612F7/dp/B08SWSLDDP/ref=sr_1_3?dchild=1&keywords=regulator+heatsink&qid=1614718799&sr=8-3

Thanks for the info. Ordered it for $5 and change and saved $27. Much appreciated. 

Hey, I ordered it last night from Dell customer/parts service for $5.35, free shipping. This would be easy to make better with higher fins. I also had the one on the link you sent me ordered (Amazon) as well at $23 +change. That one's going back! 

On the XPS 8940 I got from Dell a few days ago for $700, with a $50 coupon and tax, (see TechBargains, though no external gpu or optical drive) there are only 2 off-set holes to screw down the heat sink, not three or four on the motherboard.

Thanks for the link. I have no affiliation with TechBargains, just think it's a good deal if you need an i7 but not for gaming. I can't remember when I've used a DVD or CD so don't need the optical drive either.

Hi, I have been attempting to order the VRM for my 8940 but cannot find anyone at Dell who can locate the part number  612F7 or 0612F7.  The only item close is a CPU heat sink for $38?  Would you happen to have any additional information on your quote/invoice that might assist with ordering the VRM?

Thanks 

Someone on the posts here left this:

"If there actually is a VRM heat sink, you can try contacting Dell Spare Parts at 1-800-357-3355. Have Service Tag available..."

What are the dimensions of the xps 8940 vrm heatsink mount screws?

https://dl.dell.com/topicspdf/xps-8940-desktop_service-manual_en-us.pdf   See table 1 screw list.

Unlikely could be easily found in the retail fastener market unless someone had them on eBay.  Best bet order from Dell, depending on stock.