You won't receive many replies since this forum is reserved for feedback concerning the forums themselves, but there is more to consider than just the PSU's rating. The quality (name the brand) and age of the PSU, as well as what other components (processor, RAM, optical drives, hard drives, fans, etc) you have must also be considered.

In a hypothetical situation, you have a 300W PSU, which puts out say 285W, a reasonable expectation. Now, you already have 275W being used by other components. That would leave you just 10W for the graphics card before the PSU is completely maxed out, which would not be enough. Thus, the pure rating is just a starting point.

Fill us in on all the details of your computer or, better yet, click here to use the PSU calculator, which will help you judge what 'grade' of powersupply you need.

John