PCIe power delivery in Dell PowerEdge R420

I have a Dell PowerEdge R420 with a full-height, half-length PCIe slot. While one might imagine that this slot would feature the usual 75w power delivery, I’m finding contradictory information on the Internet. In fact, the usual figure I see is 25 watts. Can anyone confirm this number, or is it simply bogus? I’d like to slot in a halfway decent video card in there for either GPU pass through or hardware accelerated workloads. As it is I have a Radeon HD 8490 with a hacked BIOS to downclock the core and memory speeds to substantially reduce the stock 45w draw.

No conclusive answer, but 25W sounds likely. Servers commonly have x16 slots that are only wired for x8. While it may LOOK like a graphics card slot you’d find in a PC, they’re really intended for network and RAID/HBA controllers, so only giving them the standard 25W for a non-graphics slot makes sense, particularly when you consider the tight case and how much difficulty there is cooling the system using those tiny fans without adding power-hungry internal accessories.

The R420 spec sheet says specifically says:

The R420 has limited support for external graphics processing unit (GPU) technology and interface card solutions
https://i.dell.com/sites/csdocuments/Shared-Content_data-Sheets_Documents/ja/jp/Dell-PowerEdge-R420Technical-Guide.pdf

So I wouldn’t get my hopes up.

1 Like