Rugger
Splendid
What the site is actually calculating is the continuous use wattage (use a calculator to add it up). The PSUs ratings are for peak wattag and are not designed for continuous use at those levels. A hint is to take a look at the Mean Time Between Failure (MTBF) rating. For example, the MTBF on this <A HREF="http://www.newegg.com/app/ViewProductDesc.asp?description=17-103-459&depa=1" target="_new">Enermax Noisetaker 420W model EG425P-VE SFMA 2.0</A> is "greater than 100k hours at 70% of full rated load." So at 70% continuous load it will last greater than 100K hours - in other words at 294W. You would be running the system at 83% load with the 6800 Ultra. That would negatively impact the longevity of the PSU, and leave you little room for usage spikes when components cycle on/off. Modern computers require a lot of juice, expecially high end GPUs! Even with the 500W PSU, you would be running at 70%! Give yourself a little buffer and get the 535W Enermax...
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<font color=red>You're a boil on the arse of progress - don't make me squeeze you!</font color=red>
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<font color=red>You're a boil on the arse of progress - don't make me squeeze you!</font color=red>