How much of a PSU can you actually use?

Johnnytoxic · 10 Jul 2013 at 21:35

I have three graphics cards running full whack.

2x 7970's overclocked to 1120mhz
1x 7850 overclocked to 1330mhz

This is powered by an XFX true wattage 850 PSU.

According to my power measure device I'm using around 790watts.

Will this be ok do you think?

synixx · 10 Jul 2013 at 21:41

Should be fine. Good psu's are rated on their maximum continuous output level but can normally sustain higher loads for short periods of time. Cheap ones on the other hand are rated based on their maximum possible output.

Tonester0011 · 10 Jul 2013 at 21:52

PSUs like the one you have are rated for there maximum output 24/7 for something like 5 years, so that would mean 840w (about 1Kw at the wall) so you're not even making it sweat in all honesty

Defy Belief · 10 Jul 2013 at 22:44

Eh, how are you running all 3 of them together? I'm a little out of the multi gpu loop.

8 Pack · 10 Jul 2013 at 22:46

You need 1 x 1200 watt PSU per Titan when your putting 1.8v through the cards!!!

Johnnytoxic · 10 Jul 2013 at 22:57

I'm using it for WPA hash cracking, more more cards

tipes · 10 Jul 2013 at 23:04

8 Pack said:
You need 1 x 1200 watt PSU per Titan when your putting 1.8v through the cards!!!

Jeeez

panyan · 10 Jul 2013 at 23:52

top end power supplies can provide peak power higher than their rated wattage

i remember reading a while ago about an 850w psu that they were loading at 1000w and it was fine

BluD · 11 Jul 2013 at 00:09

8 Pack said:
You need 1 x 1200 watt PSU per Titan when your putting 1.8v through the cards!!!

Rofl, i bet the electrician looked baffled when ya asked him to fit 3 phase into your PC room.

Drangueos · 11 Jul 2013 at 01:26

Johnnytoxic said:
According to my power measure device I'm using around 790watts.

Will this be ok do you think?

If this is from the wall you are more than OK, if your PSU have a 80% efficiency actually your system is drawing around 650W.

An 850W PSU full loaded can draw something around 1050W from the wall.

Drangueos · 11 Jul 2013 at 01:28

here is an example of my PSU a Corsair TX850 v2,
you can see that at full loaded at 852W it is pulling 1054W from the wall.

You can read more here:
http://www.hardocp.com/article/2011/08/29/corsair_enthusiast_series_tx850_v2_psu_review/1

Johnnytoxic · 11 Jul 2013 at 08:31

Sorry I'm a bit confused with the "at the wall" remark.

So, if I have a power meter device plugged in the wall socket and its reading 790 watt, is my system actually using 632ish because its 80% efficient?

Would this mean I can make the actual power meter go up to around 1050watts ?

ubersonic · 11 Jul 2013 at 08:40

Johnnytoxic said:
Sorry I'm a bit confused with the "at the wall" remark.

So, if I have a power meter device plugged in the wall socket and its reading 790 watt, is my system actually using 632ish because its 80% efficient?

Pretty much, not every watt into the PSU means a watt out of it, some is converted to heat/etc.

Sliver · 11 Jul 2013 at 09:37

8 Pack said:
You need 1 x 1200 watt PSU per Titan when your putting 1.8v through the cards!!!

Well Kaapstad has a rig with 4 Titans. So what is he using to power them at full whack ? Dilithium crystals ?

imginy · 11 Jul 2013 at 11:12

8 Pack said:
You need 1 x 1200 watt PSU per Titan when your putting 1.8v through the cards!!!

What psu do you recommend for a 780 lightning for doing benchmarking?

ubersonic · 11 Jul 2013 at 12:24

Sliver said:
Well Kaapstad has a rig with 4 Titans. So what is he using to power them at full whack ? Dilithium crystals ?

My guess would be Kaap isn't running them at 1.8v? if im working it out right then at 1.8v the ampage involved per Titan would be so high that most PSU's wouldn't have enough on the rail to fuel more than one card /shrug.

Phixsator · 11 Jul 2013 at 12:29

Tonester0011 said:
PSUs like the one you have are rated for there maximum output 24/7 for something like 5 years, so that would mean 840w (about 1Kw at the wall) so you're not even making it sweat in all honesty

My XFX 850w Proseries XXX is sweating big time whenever i load up BF3 on two 7950 crossfired @ 925core and a mildy OCed 8350@ 4,4ghz@1,38v after vdroop. Fan are pretty freaking loud and this is all in a so called open bench scenario. Afraid to put that PSU into a case.

Sliver · 11 Jul 2013 at 13:17

ubersonic said:
My guess would be Kaap isn't running them at 1.8v? if im working it out right then at 1.8v the ampage involved per Titan would be so high that most PSU's wouldn't have enough on the rail to fuel more than one card /shrug.

Ok, well if that's the case, why the post. Was very misleading.

Drangueos · 11 Jul 2013 at 17:47

Johnnytoxic said:
Sorry I'm a bit confused with the "at the wall" remark.

So, if I have a power meter device plugged in the wall socket and its reading 790 watt, is my system actually using 632ish because its 80% efficient?

Would this mean I can make the actual power meter go up to around 1050watts ?

yes

Krisali · 11 Jul 2013 at 18:13

Sliver said:
Ok, well if that's the case, why the post. Was very misleading.

It wasn't misleading at all. He was just throwing a random fact out there.

Im guessing though it would be impossible to actually run a titan at 1.8 V though since they normally run at 1.1625v on turbo? If someone actually did that they would be braver then me (and probably richer)