Most power efficient desktop CPU?

[MadMummy76]

I've been thinking of upgrading the CPU in my home server for a while, and for this purpose I'd need the most power efficient setup possible. The computer is basically idle most of the time with a few services running in the background.

What would do this with the least power consumption nowadays? AMD, or Intel? Price is also a factor, I'd want a cheap platform but with at least 2 full length PCIe slots.

 

[LazyGamer]

I'd think you'd want to set a minimum level of performance to really get a good answer, along with a budget.

And when talking desktop parts, motherboard power draw is going to play an outsize role.

 

[MadMummy76]

I'd think you'd want to set a minimum level of performance to really get a good answer, along with a budget.

And when talking desktop parts, motherboard power draw is going to play an outsize role.

I'm thinking of the CPU as a package deal with a chipset. I don't think there is much variance in power draw between different boards using the same chipset, or is there?

Minimum performance? Let's say at least 2000 points in passmark single thread, and at least 4 physical cores.

 

[Brian_B]

Well, I would say ~most~ efficient would be an ARM variant of some kind, but I'm guessing you want to stick with x86, and finding PCI slots on an ARM is going to be challenging. Barring that, I would try to find a U-package Intel die, but that may be difficult to match with available PCI slots.

When you are looking at idle power - the CPU is going to be a big contributor, but like LazyGamer alludes to - everything else is going to add up to a lot more - particularly RAM, whatever you have plugged into those PCI slots, etc.

From what I can gather, a typical Zen3 or Alder Lake desktop-class build are going to idle in the 30-60W range. This is a fairly interesting read. I don't think core count or anything are really going to change your idle power much - everything on the CPU package is going to go into low power state anyway, so the difference between a Core i9 and Core i5 - at idle - isn't going to be much, if anything really measurable. Peak power - totally different animal, but that isn't the typical condition here.

I would also guess that a more recent generation of chip is going to be more efficient than an older one - just because of improvements in power management. I didn't pull any data to back this up, but I don't think it would be too hard to back it up.

So with that in mind, I'd go get whatever quad core Alder Lake or Zen3 you can find, throw it in with the slowest/most efficient RAM you can find, with the fewest sticks you can live with - if you can live with single channel all the better. And set any HDDs and SSDs to some aggressive power saving settings.

I don't know off hand of any way to really check power draw of specific motherboards - that would be interesting. I would hope that disabling all the stuff you don't need (extra NICs, onboard Sound, etc) would help minorly - even a watt or two adds up over the course of a few years.

That said, it's really hard to beat an ARM server that sips on about 6W at full load. This article might be of some interest.

That last linked article also lead me to this: https://www.asrock.com/mb/Intel/J4105M/ , which fits your requirements at supposedly scores about 2900 on passmark. This is an older package, late '17/early '18, so there may be updated ones.

 

[MadMummy76]

That last linked article also lead me to this: https://www.asrock.com/mb/Intel/J4105M/ , which fits your requirements at supposedly scores about 2900 on passmark. This is an older package, late '17/early '18, so there may be updated ones.

Thanks, but I looked it up, that CPU only scores ~1000 in single thread, that would be a huge downgrade, and possibly incapable of handling what I throw at it. Plus the MB only has a single x8/16 slot.

 

[LazyGamer]

That last linked article also lead me to this: https://www.asrock.com/mb/Intel/J4105M/ , which fits your requirements at supposedly scores about 2900 on passmark. This is an older package, late '17/early '18, so there may be updated ones.

There are updated ones, but not much faster - Intel isn't going to get more efficient until they start making Alder Lake-based 'Atom' CPUs. Which they can do!

Eventually.

For the moment, especially for Windows, the current aging Atom lineup isn't going to make for a great desktop experience. They do make great appliance boxes though.

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For @MadMummy76- you may want to just hop on the local 'bay and pick up a Dell / HP refurb. Not sure how large you have to go to get two x16-size slots, but that's probably as cheap as you'll want to go and likely not too bad from an efficiency standpoint.

 

[MadMummy76]

For @MadMummy76- you may want to just hop on the local 'bay and pick up a Dell / HP refurb. Not sure how large you have to go to get two x16-size slots, but that's probably as cheap as you'll want to go and likely not too bad from an efficiency standpoint.

HP and especially Dell use proprietary psus and mbs with no form factor. I already have my case and PSU I want to use. But even if I didn't I'd want parts compatibility.

What I'm really looking here is not a whole system just a chipset and a cpu that slots into it, that is capable of running windows.

 

[LazyGamer]

I'd recommend dropping your 'most' qualifier then - it implies a constraint that directly conflicts with any sort of budget or performance goal.

Anything that you can put into an LGA1200, LGA1700, or AM4 socket would fit the bill, I'd think.