Well, for that rig as it stands with no extras going to be added to it .. a Corsair CX500W or CX600W which have 34A / 40A @ 12v respectively ..
Your CPU's TDP is 95W / 8A
Your VGA card's TDP is 150W / 12.5A
.. then factor in HDD, fans and other components etc .. the 600W would be running at about the 50% load mark, so slap bang in the middle of it's best efficiency rating, and is only about £6 or so more than the 500W model ..
It might let you start tweaking things more, but no guarantee that it'll resolve any BF3 issues, but you will be running the rig from a reliable and solid PSU and that's good all round ..
AM3 965BE C3
/ 4GB Corsair XMS3 2000Mhz / GigaByte 990FXA-UD5 / Corsair H70 & 2 CM Excaliburs
/ x2 HD3870 ATOMIC Edition / Corsair 90GB Force 3 SSD / Momentus XT 250Gb Hybrid HDD / x3 Samsung F3 1Tb / Sony AD-7700 DVD-RW / Auzen X-Mystique / Enermax INFINITI 650W / Lian Li PC-7FNWB
/ Logitech X-530 / Logitech Kboard & MX620 Laser Mouse / Epson RX685 / DELL U2312HM 23" IPS TFT / MY RIG HERE