I am about to drop a second 280X in and upgrade the motherboard on my secondary rig, turning it into my primary rig. Just thinking ahead and wondering if a Seasonic 660W XP2 will cut the mustard. It is rated at 92% platinum efficiency. Specs of the proposed will be; i7 3770K @ 4.5Ghz, 1.3V Maximus 5 extreme 16Gb RAM (4*4) 2 SSDs 2 HDDs 2 180mm fans H80i Sticking all that through a PSU calculator comes out at 690W. Now I know there is always a degree of over provision built in to these calculators to sell units, but how much we talking here? Think it's do-able?
using the calculator on pcpartpicker.com just the two 280x use 500 watts. so I'm guessing not. would recommend Seasonic 760 watt or Corsair RM 750 watt
A 660w will manage most of the time (I reckon you'd struggle to get the rig to pull more than 600W from the socket without benching), but you'd be safer with a decent 750 if you're planning to cane them. And I suspect you are
The efficiency rating has nothing to do with how well it powers components up to it's rated wattage, it's how much power it uses to generate that power. For example and keeping it simple for my own benefit (it's late and I'm squiffy ), a 90% efficient 900W PSU will draw 1kW to produce 900W. So you can work out your max pull from the wall by calculating (660/92)x100.
I agree with all that, but those 280s will by themselves only pull a maximum of 480w when fully saturated, leaving the OP with 180w to power the rest of the rig. Therefore I think it's doable. Sensible? Depends how comfortable you are running a PSU at the top end of its potential from time to time, but I'd take a punt. Must sleep now
Cheers for the input then guys. Looks pretty clear cut; doable, but only for the brave. Which I'm not. Looks like I'm in the market for a new psu too then.
You can do it. But I've always treated picking power supplies like I treat audio. IE - never turn the volume knob past 9 o'clock. So that means having an amp that's at least 1/3 more powerful than the speakers you run. So it's the same for me with PSUs. Calculate the actual wattage pull and then add 1/3 on top. I would say a 750w. I say that because I'm running a 7990 with 6 hard drives and a CPU that's pulling a good 220w on load.
Why not have a go with it and invest in a cheap watt meter? Run a few benches and from the draw from the wall you can work out how hard the PSU is working and decide yourself how happy you are running it at that sort of peak load (and bear in mind that efficiency will vary with load, 92% is peak and won't be delivered across the entire usable range). PSU calculators run on the conservative side so you might find that real world (or even bench-world) the PSU runs well within what you're happy with.
Yeah, if you've already got the PSU just buy a wall meter, play some games, see what kind of draw you get. I suspect you'll be fine but no harm in finding out.
