How to measure PSU load?

Cenedd · 14 Apr 2020 at 11:49

Hi all. Any good ways (read: easy!) of measuring how much load you're pulling from an ATX PSU? Tried a couple of PSU calculators and they give very different results of 450W and 650W. Given that I have a 700W PSU, just wondering how much headroom I have to see if I can afford to increase the power target on the GPU from 250W. I was thinking a kill-a-watt type device would show me the mains draw and wattage but does that translate into PSU load well enough to give a good idea of how much it has left?

Many thanks,
Gareth

Cenedd · 14 Apr 2020 at 20:00

pastymuncher said:
A plug in power meter for around a tenner will give you a idea of how much you are pulling from the wall. Be warned though, the things are very addictive and you will end up plugging every electrical item in the house into it to see how much power everything uses.

That's what I was originally thinking but wasn't sure if/how well it translated into PSU load. Logically there will be some inefficiency but also it doesn't break it down into 12V and 5V loads. Could be that I'm just overthinking it as usual though.

Acme said:
What is your specification? I run 2x overclocked R9 390 8GB's and an overclocked i7 + watercooling and a few drives and lights and stuff, on a 750W PSU. The recommended PSU for my spec is about 1000W.

Overclocked i7-6700k (4.4GHz all cores turbo - nothing world-beating), Titan X Pascal, 2x M.2 SSD, 2x DDC 18W pumps, Aquaero 6, Farbwerk, Aqualis res (fill-level module), flow sensor, 2x 140mm fans, 4x 200mm fans, some LEDs, currently a BluRay drive nastily hanging out the side (as ya do), various USB devices including external soundcard/DAC.

The thought occurs too that, having done a little research, the result of overclocking the card would probably be about 10fps and might involve a 20% increase in power draw (ignoring cooling) so I could possibly just go for it for curiosity's sake and then scale it back afterwards. Hopefully the PSU should self-protect rather than blow and/or I should get instability before then and not trash the SSD content. Sorry, thinking 'out loud' here.

Cenedd · 15 Apr 2020 at 07:53

Well, that works for me. I shall have a play when I'm allowed the time. Be interesting to see how well my loop does for performance rather than its normal target of silence.

Cenedd · 17 Apr 2020 at 11:06

ezekial said:
Post the results and your conditions so other people can see too

Will do. I'll update my project page when I do. Trouble is that I'm waiting for deliveries. OCUK have sent me a bottle of coolant and a T-piece but I'm waiting on a drain valve and a backplate for the GPU. Would rather have the backplate on before I push it - I know it's minimal heatsinking but every little helps. Also, I'm very low on coolant at the moment - ordered what I thought was enough but found it wasn't. Have to drain it to install a second drain valve - yeah, the irony - as my loop has evolved and now requires two; one in each gravity-split half. Don't want to go filling the rest up given that I'm going to be draining it. Stuff will turn up eventually and then I'll get my finger out!

My PSU, for reference, is a Nesteq ASM X-Zero 700W. Generally been good but it would have been nice if they'd not glued the pins into the plugs so you can't de-pin it. Just checked when I bought it and it's 8 years old already. Can't say I've not had my money's worth out of it!

Cenedd · 17 Apr 2020 at 11:29

Excellent, cheers. Looks like mine should be between 80 (s=80 PLUS standard minimum) and 89% (quoted 'up to') efficient so that gives me a good guide.