PC Power Draw?

[Topcat]

Re: PC Power Draw?

Nah math is really old, it can't tell the difference between the real and imaginary components, i.e. phase angle of current draw.

Thus I'd can't even give it an accuracy assessment unless you're testing with a device with a PF very close to 1. It'd be completely wrong otherwise.

That would probably be beyond my knowledge.... While the numbers yielded seem to be in realistic ranges, the rest of that I can not intelligently answer....I just did the test and read the meter.

[eccerr0r]

Re: PC Power Draw?

Nah math is really old, it can't tell the difference between the real and imaginary components, i.e. phase angle of current draw.

Thus I'd can't even give it an accuracy assessment unless you're testing with a device with a PF very close to 1. It'd be completely wrong otherwise.

[Topcat]

Re: PC Power Draw?

Can that Sencore PM157 even tell the difference between real watts versus apparent amps? I guess it doesn't matter if you have APFC but seems like a piece of equipment that has passed its prime...

Is this like the 'new math'? Raw amperage pulled from line, when did this change? Old meter? Indeed. Extremely accurate? Probably not. Good roundabout? I'd say yea. Unless someone has something better than a clamp meter or inline from harbor freight, feel free to share it.

[eccerr0r]

Re: PC Power Draw?

Can that Sencore PM157 even tell the difference between real watts versus apparent amps? I guess it doesn't matter if you have APFC but seems like a piece of equipment that has passed its prime...

[Topcat]

Re: PC Power Draw?

Test system:
Supermicro H8DA3-2
2x AMD Opteron 8393 Quadcores @ 3.1
64gb RAM
2x Quadro FX5800's in SLI
4x 2.5" 15,000RPM SAS HDD's in a RAID5

The test bed is the above system being monitored from line with a Sencore PM157 Power Monitor on the 3A scale.



Fully booted, sitting idle. Consistent between 1.8~2.0 amps.



Same for web browsing, with minor up spikes during scrolling or graphical actions, didn't vary much from idle. A 4k youtube video playing kicked it up to ~2.2A during playback.



Q3A (only game on the system at this time) loaded/playing is pretty consistent @ 2.3~2.5 amps.



Now I'm running Novabench. This is the HDD write test; steady 2.5A, both reads & writes.



This is the GPU test. I'm not sure if Novabench takes advantage of SLI or not, but it bounced the needle off the scale throughout most of the test. I retested it on the 10A scale, and it never broke a 3.8A draw.



Boot time, it danced around a little, but never pegged it out on the 3A scale.

That concludes today's test.

[eccerr0r]

Re: PC Power Draw?

Ah ok, perhaps this should be placed into the "Lounge" subforum then... was a bit confusing why such a topic as it seemed fairly well known that higher performance PCs use more power in general...

I have too many PCs, one of which is my PVR that I run 24/7 and it's probably like 80W or so idle, and I am suspecting near 130W or so if I'm submitting batch jobs to it. No GPU, just needs to pull recordings off the air and be able to play them back on the TV it's attached to. It's a really old PC and its onboard chipset graphics (not even CPU graphics) is sufficient for that.

[TechGeek]

Re: PC Power Draw?

Was this supposed to be a "chat" question or "why is this" question?

I find my pc's with GPUs to be the worst power consumers in general... GPUs are hungry....

Supposed to be a chat question.

[eccerr0r]

Re: PC Power Draw?

Was this supposed to be a "chat" question or "why is this" question?

I find my pc's with GPUs to be the worst power consumers in general... GPUs are hungry....

[TechGeek]

Re: PC Power Draw?

With AC, you can have 10A @ 120V which is 1200VA, but could only be 100 watts. This is an extreme example, as is 10A worth of oil caps across the line; in this latter case, you'd only be drawing a few watts or so.


You need to consider not only power factor, but also note that a non-TRMS can (will?) read higher or lower, especially with loads that draw huge currents for a small portion of the sinewave- doubler or rectifier input SMPSes.

If your computer power supply has APFC, then input current times input voltage will be very close (.95-.99) to input watts. This, of course, is total input power; the computer's load plus losses in the power supply.

APFC here. And I think that this actually *is* a true-RMS current meter, but that doesn't matter a lot when your PF is .98 or similar.

[kaboom]

Re: PC Power Draw?

With AC, you can have 10A @ 120V which is 1200VA, but could only be 100 watts. This is an extreme example, as is 10A worth of oil caps across the line; in this latter case, you'd only be drawing a few watts or so.


You need to consider not only power factor, but also note that a non-TRMS can (will?) read higher or lower, especially with loads that draw huge currents for a small portion of the sinewave- doubler or rectifier input SMPSes.

If your computer power supply has APFC, then input current times input voltage will be very close (.95-.99) to input watts. This, of course, is total input power; the computer's load plus losses in the power supply.

[TechGeek]

How much power does your system pull at the wall?

My main computer pulls ~1.2/1.3A (average line voltage 124V) at the wall. Roughly 160W idle. 1.8-2A when rendering, and 2.5-3A when the CPU and GPU are both heavily loaded.