IsaacJDean
New member
Aren't many power supplies most efficient around the 50% load mark? Also, like Tom said, it's not all about watts.
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2x gtx680 ftw 4gb and i5-3570k overclocked a little. Size power supply will i need?
- Thread starter GingerHamster19
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MacLeod
New member
Its the 50-75% range where they work their best. Those power consumption numbers are with the system at full load which your rig wont be running at very often so the
majority of the time, it'll be running closer to idle and when at full load when its drawing 500 watts, you're still in the 75% range with a 650 watt power supply.
And even if out drop out of that 50-75% range, you'll still be getting good efficiency with a quality PSU. As long as you're not running at 5% capacity or something ridiculous like that, efficiency wont be a big concern.
Again, I'm not saying 650 is the perfect number. A 750 would work perfectly well too and give you headroom for water cooling and extra hard drives and such.
majority of the time, it'll be running closer to idle and when at full load when its drawing 500 watts, you're still in the 75% range with a 650 watt power supply.
And even if out drop out of that 50-75% range, you'll still be getting good efficiency with a quality PSU. As long as you're not running at 5% capacity or something ridiculous like that, efficiency wont be a big concern.
Again, I'm not saying 650 is the perfect number. A 750 would work perfectly well too and give you headroom for water cooling and extra hard drives and such.
MacLeod
New member
:headscratch:
iBeInspire
New member
a Pair of 680s ALONE Pull 500w at full tilt, once you factor in CPU load power draw, and overclocking, your looking at a good 600/650w.
Now, this doesn't mean you need a 650w PSU,since all this power has to come down the 12v rail.
This means that you need a PSU that puts out ATLEAST 50 Amps (600/12) on the 12v rail, or preferably 55 Amps (650/12, rounded).
This is alot to ask of a PSU, and I'd suggest going for a quality 750w Corsair unit, or maybe a Seasonic.
Now, this doesn't mean you need a 650w PSU,since all this power has to come down the 12v rail.
This means that you need a PSU that puts out ATLEAST 50 Amps (600/12) on the 12v rail, or preferably 55 Amps (650/12, rounded).
This is alot to ask of a PSU, and I'd suggest going for a quality 750w Corsair unit, or maybe a Seasonic.
MacLeod
New member
I'm not trying to be argumentative but the reviews just don't show this. They measure total system draw at the wall socket and its less than 500 watts at full load which would translate to around 400 actually being drawn from the PSU. I'm at work on my phone now and can't dig up a bunch of links but Google GTX680 SLI review and check out the power consumption numbers.
I agree with you though that a good quality 750 would definitely fit the bill.
iBeInspire
New member
I'm not trying to be argumentative but the reviews just don't show this. They measure total system draw at the wall socket and its less than 500 watts at full load which would translate to around 400 actually being drawn from the PSU. I'm at work on my phone now and can't dig up a bunch of links but Google GTX680 SLI review and check out the power consumption numbers.
I agree with you though that a good quality 750 would definitely fit the bill.
I did the whole Googling thing, that's where I got the numbers from
And the one review I read (Fair do's, I should have read a few, but still) said that they drew 473w under load, from the wall, for JUST the GPUs...
I rounded to 500w for safety, but apart from that I left the results unaltered...
MacLeod
New member
I did the whole Googling thing, that's where I got the numbers from
And the one review I read (Fair do's, I should have read a few, but still) said that they drew 473w under load, from the wall, for JUST the GPUs...
I rounded to 500w for safety, but apart from that I left the results unaltered...
That's the Tech Power Up review right? That's the one oddball. Everybody else shows less than that for full system draw and they show nearly 500 just for the cards. Weird.
Either way, we both agree that a 750 would be great so we're both right.
iBeInspire
New member
That's the Tech Power Up review right? That's the one oddball. Everybody else shows less than that for full system draw and they show nearly 500 just for the cards. Weird.
Either way, we both agree that a 750 would be great so we're both right.
xD Everyone wins! :lol:
I know this is resolved, but I thought I'd post my two cents about what power supply would be needed.
Theoretically speaking, at maximum load a single GTX680 would be pulling just shy of 200w. Double that, add 100w for the 3570k and another 100w for the other components and at maximum load level (ie: both CPU and GPU running stress tests) the system probably pull around 600w, though it's usually less than 500w during gaming load (second card usually pulls less than the first, due to in-game scaling) - as most reviews seem to show.
Personally I'd be tempted to jump up for a 850w just to leave the power supply at a lower load level, but a 750w would probably be fine.
From what I've seen the HD7970's seem to perform better with multi-monitor setups though, even before the 12.11 driver updates they were notably ahead of the 680's. That may be worth considering too, though in that case a 850w would definable be preferable, so do keep power consumption in mind (especially with the Ghz editions, which do pull a lot more power).
Theoretically speaking, at maximum load a single GTX680 would be pulling just shy of 200w. Double that, add 100w for the 3570k and another 100w for the other components and at maximum load level (ie: both CPU and GPU running stress tests) the system probably pull around 600w, though it's usually less than 500w during gaming load (second card usually pulls less than the first, due to in-game scaling) - as most reviews seem to show.
Personally I'd be tempted to jump up for a 850w just to leave the power supply at a lower load level, but a 750w would probably be fine.
From what I've seen the HD7970's seem to perform better with multi-monitor setups though, even before the 12.11 driver updates they were notably ahead of the 680's. That may be worth considering too, though in that case a 850w would definable be preferable, so do keep power consumption in mind (especially with the Ghz editions, which do pull a lot more power).
