I've recently bought the Sapphire Radeon HD 2900 Pro graphic card cuz i'm building a new comp, and when i was reading som info on the package i saw that it was recommended 550W power supply or greater... so the problem is that I have a Antec Sonata III 500W (http://www.antec.com/us/productDet [...] odID=15137), will it be able to run it?

You should be more than fine. Ive got a sapphire 2900 pro, with a 500w tagan power supply (which ain't the best quality) and Ive had no problems soo far. The rest of my system is: core 2 duo e6300 oc'd to 2.6ghz, ASUS P5-B motherboard, 2gb corsair ddr2-800 and a samsung 250gb HD. The case has 1x140mm fan, 1x120mm fan, and 1x80mm fan. My pro is still at stock, and i wanna oc it to 700mhz core (its at the stock 600mhz speeds now). Above that I dont trust my power supply as the exhaust air from it is rather warm, and in addition I'd like to keep it (the power supply) until the end of this year at least, so I dont want to be stressing it too much. Soo on a 550w supply, better quality than mine, you should be more than ok. I know the pro will/should oc to about 820mhz core, which should wop a 3870, but I'll hang on until I get a better PSU next year.

Whats the rest of your system?

For reference here's a review from firing squad, says total system power consumption under load with the card was 300w. The powercolor card only oc'd to 780mhz, but Ive read alot of forum posts with people saying they've got 800+ mhz. Seeing as the GPU and memory on the card share the same heatsink, if you held of oc'ing the ram by very much, that would lend a bit of heat dissipating capacity for a higher core overclock. Since the 2900s are swimming in memory bandwidth anyway then a higher core clock might make a better bet over memory oc'ing anyways. If you plan to oc that is.

Yeah, the Earthwatts 500W has 34 amps on the 12v rails which is higher than many larger PSU's. You won't run two of them on that power supply, but you will be fine running a single 2900 pro.

[quotemsg=1797749,2,299418] My pro is still at stock, and i wanna oc it to 700mhz core (its at the stock 600mhz speeds now).
dont stop there mine handles above XT stock speeds fine
in fact, i may flash it one of these days....

hey i have a 2900 pro running on 750w power supply and cuts out somtinmes

its silverstone strider and puts alot of juice on triple crossed quad rails

Does that need an 8pin connector for o'cing (overdrive) or just 2x6pin?

Needs 8 pin for O.C'ing... typically although it can be cow-boy'd

I'd not bother though. Find a 6 to 8 pin adapter... slightly safer.

Let me restate (I know what your saying, I was trying to state this)

Are you running two 6pin pcie connections or one 6pin and one 8pin since the 8pin may be needed to use the overdrive feature?
I was addressing this comment:
"hey i have a 2900 pro running on 750w power supply and cuts out somtinmes"

I was not recommending something unsafe, I would recommend using something like this:
http://www.performance-pcs.com/cat [...] 191c68e9f4

Thanks for clearing that up I suppose??