R9 290 xfire PSU requirements

Well as the launch of the r9 300 series approach I'm looking at adding a second 290 to my system. Only thing is my PSU is a 750 Watt PSU and I'm not sure if that is enough. Well I know it's just enough from looking at PSU calculators. They say it will need about around 700 watts. But my question. Is it safe to run a PSU at close to max power for extended amounts of time? If not what size psu should I look into? Also my PSU is a corsair HX750 psu

Need more specs on the rest of the system to really determine if you're Ok with a second card. If you're running an Intel Cpu you should be fine with a second card even with a mild OC. If you're running a Fx 8xxx AMD chip and are Oced you probably will need a bigger Psu.

Well I have a fx 6350 overclocked to 4.5ghz, but if I have to I don't mind leaving it at stock. If I run the psu near Max I don't mind.

I just went on http://www.extreme.outervision.com/PSUEngine

And entered every thing in my PC and it said minimum wattage 668 and recommend 718. With everything at stock. I'm guessing 750 will be enough. But it's probably cutting it close. If I get a second 290 I will probably just run every at stock.

This is where you're at, a R9 290 TDP is 275w a Fx 6350 is 125w at stock. Once you have all 6 cores on the Fx locked on, all the time, the wattage goes up significantly. At 4.5 at 100% load you're likely closer to 175 w, I'm guesstimating here. Luckily you have a quality Gold rated Psu. So if at any time when running a second card at stock clocks, you're running the Cpu and Both Gpu's at 100% you're going to be close to 700W. It's also doubtful you will ever have the Cpu and both Gpu's at 100% load at any time unless you're benching it. I would say even with a mild Oc you will be able to run 2 R9 290's without issue. Now if you find that the rig is shutting down while using it, assuming you're gaming. Then you're drawing too much power and you will need a bigger Psu.

Well I think since there only life $20 in going to buy a kill a Watt meter. If so what would be the best. Way to stress my cpu and gpu at the same time? Just run prime 95 and a bench marks like Valley? I know gaming will not stress every thing to almost 100% but if I have close to 275 watts left then I will not worr about my PSU being to small

I use a Kill O Watt meter myself only because when I was really pushing my Fx 8350 ie 5.0+ Ghz for benching with a power hungry GTX 580 lightning. I was having problems with the rig just powering off instantly. This was when I was running my Seasonic X 650 gold Psu. I never realized that these Fx Cpu's draw as much power, when pushed, as they do. I'm attaching a pic of my Cpu at 5.2 and the Lightning as far as I could push it, running heaven and Prime 95 at the same time. That's 827w from the wall! I was running my CM SP 1000W when I took it. Now with the Kill O Watt you have to factor in that it isn't 100% accurate and also the Psu efficiency. So my actual power consumption might have been around 725W, guesstimating. That all said running Heaven/Valley and Prime 95 is totally unrealistic as far as what your power draw will be gaming. What I would do is just leave your system as is, plug in the Kill O Watt and see what it reads while gaming.

Ive seen modded 580's do over 700W themselves (under LN2). I wonder just how much that CPU was part of that value.

EarthDog said:

Ive seen modded 580's do over 700W themselves (under LN2). I wonder just how much that CPU was part of that value.

Click to expand...

This wasn't modded ED, just Oc on it's normal BIOS, no additional voltage mods other then what Afterburner allowed. I have done some testing on the Cpu. At 5.0 on all 8 it's pulling around 300W. That said my Fx 8350 is a bit of a power hog and Clapper is using a 6300. I'd bet under normal circumstances adding another R9 290 with a Hx 750 should be fine. Benching probably not.

Agree,

Stock you should be ok, if you want to pound on it you will need more

Listen to the Witchdoctor!

I just ran Aida stress test on my rig below with the cpu at 4.4Ghz, gpus stock (1000core 1300 memory) 12 fans maxed out and 2 D5 pumps going full bore and my Kill A Watt meter measured @750 watts. I use MSI afterburner and enabled both gpus at 1100 core/1400 memory with max gpu vcore and the meter rad 880 watts.

Clearly OCing the gpus will really ramp up the power demand. Fortunately, my PC P & C 1200W Mk III Silencer is built like a tank and easily handles this.

Hmmm, gonna have to get my hands on a kill-o-watt and see what my system draws out the wall. I'm sure my 1300w Zeus will handle it just fine