Hello i have been running my comp now for awhile and its rock solid, but i want a little more fps so i deiced to go crossfire, i have 1 asus 3870 right now and im going to get another, and i was wondering if my rosewill 550w dual 12v rails 35a heres more specs http://www.newegg.com/Product/Produc...82E16817182030, will this be enough power for them? I went to this power supply calculater http://extreme.outervision.com/psucalculatorlite.jsp and it told me my reccomendded was 354 watts full load for this crossfire setup, and that seems really low so that seems legit but i am jsut concerned if it will be enough power, i am not overlcoking anything and here are my specs...

Asus P5E X38 chipset
Core 2 duo 2.66ghz
Corsair dominator DDR2 1066mhz
Asus 3870 512mb
74gb 10,000 rpm Raptor
Diamond 7.1 extreme sound pci card
three 80mm case fans, one 120mm
Sunbeam Transformer case
17 in. Proview vga LCD monitor

This might help you. I have a professional digital watt meter, accurate down to 1 watt that I used to measure my system. I have an Asus pk5-e, Q6600 quad core (more power hungry) over clocked to 3.4ghz which makes it use even more power. 4GB of ocz DDR2, 2 500GB hard drives from western digital (same company that makes yours). 8800GT which draws a bit of power. An Antec 900 case with 5 fans, plus Tuniq Tower.

Over clocked and running a heavy load of prime95, it uses 290 to 297 watts. I tried games and other software and it never uses more than 300 watts total really. It also didn't exceed 300watts in any game either.. But that is over clocked to the max.

Without out it being over clocked and being idle it uses 235 watts, and 255 when under heavy load roughly. So that would be less than a 50% load on your power supply which is fine. 46% actually.

So this shows you that the figure you found probably is legit and you'd have some room to play with to add another card. I'm not sure how it works out on your system, but I'd think your psu can handle it just fine.

That seems like a reasonable figure. It reckons my AMD X2 6400+ system
should take 217W at 100% load. The actual measured power consumption
at 100% load (both cores) is 220W so it seems quite accurate. When the
CPU is overclocked to 3.62GHz, the power consumption is around 250W

AMD x2 6400+ at stock speed 3.2GHz. 2 x 1GB DDR2, 1 x SATA HDD,
Nvidia 7300, 1x DVD-RW.

Go with a Corsair 550VX/520HX or PP&C 610.

^^ Agreed, I also concure that 550w is enough...but not from a Rosewill. You better get something of better build quality.

Although some of the bigger Rosewill units have received good reviews at Jonnyguru, the one you have more likely lives on tier-5 ("Do not buy" ) of the PSU listing at http://www.tomswiki.com/page/Tiere [...] gs?t=anon. As such, I would not trust it with any load over half of its rating. When Jonnyguru tested some cheap PSUs, all but one of them croaked dramatically, some at the 60% mark.