So I'm planning some upgrades to my build. My current PSU is a really nice modular 450W OCZ. I don't really want to have to buy a new one if I don't need to. Would 450W be able to supply an AMD Phenom 955, ATI Radeon 5850 on a mid/high-end MOBO and DDR3-1600 RAM? I'll probably do some minor OC'ing of the components as well. I did the newegg PSU finder thing, and it recommended a 550W PSU. So... thought?
Sorry man no heres why
500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended (600 Watt and four 6-pin connectors for ATI CrossFireX™ technology in dual mode) for the 5850
plus running fans on a case,hard drives, cd drives usb items speakers no a 450 wont cut it sorry
For whatever it is worth, I am presently running an OCZ Stealth X stream 600, [which Hardwaresecrets.com says OCZ could have sold as a 700w], and it is just fine for any single video card system, OCZ now has a Stealth X ETC,ETC,,, 600-2,which is a slight improvement on the original,no complaints here...
One of my systems has an OC'd Q9550, 4 GB RAM, a GTX260 - a card with similar power requirements to yours, a Gigabyte EP45-UD3P motherboard, 3 hard drives and an optical, and a Soundblaster card all powered by a Corsair 750TX.
Running 3 instances of Prime95 to load the CPU and 3DMark06 to load the GPU, it pulls 375 watts from the wall as measured by my Kill-a-Watt meter. Figuring 80% efficiency, the system pulls 300 watts from the PSU.
It takes surprisingly little power to power most systems.