I'm just about to buy a Radeon HD 5850 for a budget build. However, the PSU i chose is Corsair CX 430W 80+ Bronze. Will this 430W PSU power the HD5850? I'm going to use it with an Intel Core i3 3220 3,3Ghz with stock cooler on a ASRock B75M-DGS mATX mobo. I'm not going to have a DVD drive as well, maybe that will leave some power for the GPU.
Peak power is about 130w. It's been awhile since I last saw a review of my card.
I would say you should be okay. The CX 430W provides a maximum of 384w on +12v rail where most components draw power from. That's assuming no more than 46w drawn from the +5v (motherboard) and 3.3v (RAM) rails since total max power output is 430w. I generally prefer the not going beyond 80% of the maximum since the more stress you put on a PSU, the shorter it's lifespan can be. Plus it allows for some room in case the power draw spikes up temporarily. The means a maximum load of 307w.
Component and the approximate power draw:
Radeon HD 5850 = 130w
Core i3-3220 = 65w
1 Hard Drive = 12w
1 Optical Drive = 12w
1 120mm fan = 12w
1 CPU Fan = 8w
Total Estimated Wattage = 239w
Based on the above, you should be fine. There should be plenty of breathing room for the +5v and +3.3v rails.