Can anyone tell me what PC will draw more power?

spacemanspiffy@lemmy.world to No Stupid Questions@lemmy.world – 32 points –

This is probably a stupid question, since 2 > 1, but here goes...

I have a home server. It's a ComputerLINK 1U rack server I bought off eBay some years back. It has 2 CPUs, Intel Xeon E5645 2.4Ghz(https://ark.intel.com/content/www/us/en/ark/products/48768/intel-xeon-processor-e5645-12m-cache-2-40-ghz-5-86-gt-s-intel-qpi.html). It also has two 750W power supplies, but I have one unplugged. It also has RAM and 5 HDDs.

I also have the guts of my old desktop PC. The CPU is an AMD FX8350 4Ghz(https://www.amd.com/en/products/cpu/fx-8350). The motherboard is some ASUS model, I forget and don't want to check right now. A potential PSU would be 500-600W range.

My question: I am considering moving to use my old PC parts as a new home server. One benefit is to cut down on the noise (rack mount PC fans are LOUD). But the real gain I would want is on power savings. So, if RAM and the multiple HDDs all stay the same, but I moved them to the AMD/ASUS CPU/motherboard, can anyone definitively say this will be more power-efficient?

I am not very knowledgeable when it comes to electrics or power consumption, and am just looking for someone to confirm for me. I am aware that the AMD CPU still isn't an excellent choice for an always-on machine, but it could be an improvement.

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A few points:

  • The redundant (second) PSU on the server is not using power (at least, not much) unless the other fails. Its job is to be available if the other PSU fails, or if power is lost (you typically have them on different PDUs and fed by different UPSs.
  • Almost any desktop is going to use less power than a server, as servers don't bother with power-saving features or power states other than full tilt into oblivion.

I won't go into the research required to give you a quantitative analysis, but suffice to say that a server > desktop in terms of power usage IN MOST CASES. Of course, if the desktop is running four 250w GPUs and running crypto or other full-time workloads, it could exceed the server, but all things being equal, well, you get the point.

While actual power consumption won't be much apparent power (VA) will be a measurable amount. If you're connected to a UPS and it's not a super modern server then it's apparent power will be a decent amount. As a normal end user you don't pay for this, but if you're trying to spec out a UPS you'd want to calculate it and factor it in.

The FX 8350 isn't a very power efficient CPU, but two E5645 in a server is going to use a lot more power at idle (and load) than the FX. Servers actually have pretty manageable power usage, but idle consumption of a dual CPU system will always be more than a single CPU system.