Office computer only 40w at load? Is that possible?

[Red Squirrel]

So we are looking at new video cards at work to drive 3 4k monitors since the built on is being pushed too hard (they are hooked up now) and wanted to see how much leg room we have on the PSU, it's a 200w so figured we're probably cutting it super close. I used my true RMS meter to test at the wall to get an idea of draw and got 0.4 amps at a decent load (was at work and on windows so kinda had to improvise, no easy access to coding/scripting like Linux) so downloaded Furmark and then just ran dir /s in a bunch of consoles. Kinda crude but got the cpu to like 60% usage.

I got it up to about 0.4 amps. At idle it was like 0.1. I tested the meter on a 3.5 amp fan and got 3.5 amps so I think the meter is working ok... but I don't get how the computer is only using 40w. It's a HP low profile type PC so I guess it COULD be, but it's not like it's a mini thin client or anything either, it's still a full x86 machine with a normal desktop processor. Is this reading actually possible or could my testing somehow be off?

 

[VirtualLarry]

What CPU did it have in it? Sky / Kaby / Coffee Lake are all in that ballpark.

 

[dave_the_nerd]

0.4A @ 115v is 46w.

A CPU with IGP, motherboard, and RAM/HDD or SSD, with the CPU puttering along at 60% load, and a relatively efficient PSU?

Yeah, that'd be about right.

 

[Red Squirrel]

What CPU did it have in it? Sky / Kaby / Coffee Lake are all in that ballpark.

Not too sure of the exact model but it's an i5 if I recall, I'd have to check again. Not sure of the other exact specs like motherboard but it would be fairly proprietary so could very well be they are optimized for low power. Like that mobo probably uses less power than a typical higher performance one you'd buy for a home custom build.

This kind of has me thinking buying a bunch of off lease business class boxes like this could make a nice efficient VM lab environment.

 

[XavierMace]

At 60% load that doesn't sound difficult to believe at all. My dual processor Westmere-EP based servers with 128Gb of RAM, a couple of NIC's and a few SSD's run around 160w at those load levels. That's effectively two 80w computers. Pull some memory, NIC's, and all but 1 SSD and I'd have no trouble seeing that drop down at least another 20w. People wildly over-estimate the power usage of modern computers under "normal" loads.

 

[Red Squirrel]

Yeah I tend to use my Atom based server as a base line so I expect anything more powerful to use more power, but is newer stuff even more efficient then? My Atom based server uses about 75w idle.

 

[dave_the_nerd]

Yeah I tend to use my Atom based server as a base line so I expect anything more powerful to use more power, but is newer stuff even more efficient then? My Atom based server uses about 75w idle.

Newer stuff is more efficient, but I'd be willing to bet that most of your 75w use isn't your CPU. How many HDDs do you have in that thing, like a dozen?

 

[Red Squirrel]

Newer stuff is more efficient, but I'd be willing to bet that most of your 75w use isn't your CPU. How many HDDs do you have in that thing, like a dozen?

That particular box does not have much, just a small spinner and a fan. Just a small 1U box. Though it does also power an arduino and relay controller but think I had tested before all that was hooked up. And yeah the cpu would just be one part of the load of a computer, motherboard and other components probably uses a decent amount too. Video cards tend to be what use the most, like my gaming machine uses 300w easily.

 

[XavierMace]

75w idle is way high for an Atom. Killawatt says the gaming system in the house with 6600k, 32Gb RAM, GTX1070, M.2 SSD, 2x2.5 spinners is idling at ~90w, that's including a 4k LCD.

 

[JoeBleed]

oh the HP ProDesk 650 desktops we have at work, it sounds right. and they're a few years old now. not sure about yours, but the power supplies in these are proprietary as hell. they have very few wires coming from the power supply. If you haven't checked yours, check it before you put a video card in that requires additional power plugs. I tested the ones here and it was crazy low, from what i'm used to. but i was pissed when i saw the power supply.

 

[Red Squirrel]

Oh yeah most clones will have proprietary PSUs, only video card option is something that is low profile and does not require external power. Unless you want to start to splice into the 12 volt rail but probably not something you want to do in a business setting.

 

[JoeBleed]

Oh yeah most clones will have proprietary PSUs, only video card option is something that is low profile and does not require external power. Unless you want to start to splice into the 12 volt rail but probably not something you want to do in a business setting.

for these prodesk 650 desktops, i don't mean just a proprietary size so you can only fit one in the case. i mean wiring and connectors. there is no 20 or 24 pint atx connector. they use their on. i have yet to open up one of the supply units nor measured to see what voltages they're supplying.

this is all of the connectors you get. https://www.newegg.com/Product/Product.aspx?Item=1HU-001R-00292

 

[Red Squirrel]

for these prodesk 650 desktops, i don't mean just a proprietary size so you can only fit one in the case. i mean wiring and connectors. there is no 20 or 24 pint atx connector. they use their on. i have yet to open up one of the supply units nor measured to see what voltages they're supplying.

this is all of the connectors you get. https://www.newegg.com/Product/Product.aspx?Item=1HU-001R-00292

Yeah did not pay attention to connectors but I believe it. When you have a machine like that and the PSU dies it's pretty much game over as you'll never find one that fits. I guess one thing that is also possible is that the voltages are different too, though I imagine for PCI-e slots, USB etc they still have to follow the standard right? Like it's still going to have 12 volts, 5 volts etc available to it?

 

[JoeBleed]

I would guess that they're taking the approach similar to laptop power supplies. just bigger, internal, and cooled by a fan. May only be 12v with everything regulated on the board. But again, i haven't taken the time to try and measure it.

 

[Red Squirrel]

That would make sense actually especially if they can more or less have the exact same electronics and just a different box. I guess if a laptop can use well under 100 watts then why not a workstation too. Just need to design the motherboard around power efficiency.

 

[serpretetsky]

i know this is kind of late, but Im curious what the same computer will show running the same test but swap out "dir /s" for prime95 stress test (still run furmark)

 

[Red Squirrel]

Was kinda spur of the moment and was not sure what other program I could get to do cpu testing but good to know for next time. Normally I just do a bunch of while(1); loops if I'm on Linux but was not sure of a compiler I can use in Windows.