|OtheHill's second link refers to a real world test of how much power a system with a 6950 card installed draws in total from the power supply - 297 watts max - , however, there's a statement before the results...|
"So while the system might draw 400 watts in our test system, placing it into your own PC with a number of other items, the draw is going to be higher. "
However, hard drives draw very little current, and even if your mboard and cpu and other components draw more current, your present power supply model will still handle whatever that is fine.
What AMD says.....
AMD Radeon™ HD 6950 Graphics
■500 Watt or greater power supply with two 75W 6-pin PCI Express® power connectors recommended
■Certified power supplies are recommended. Refer to http://ati.amd.com/certifiedPSU for a list of Certified products
■Minimum 1GB of system memory
Max power 500W
Peak power 600W
one 6+2 pin PCI-E connector
Your power supply model was not designed to have 600 watts drawn from it continuously, but 500 watts can be drawn from it continuously.
In most if not all cases, the max capacity rating of the PS is an intermittent rating. It's recommended that you do not load your PS to any more that 80% of that rating if you are going to be using something that puts a constant load on it, such as playing a recent game for hours on end.
You need to buy a suitable a wiring adapter for the second power socket on the 6950 card.
They're usually easily available locally from places that have lots of computers parts.
You need one that has two molex connectors on one end, one pin PCI-E connector on the other end.
E.g. like this one:
DO NOT buy a wiring adapter that has one PCI-E 6 pin connector on one end (that plugs into the one 6 pin connector coming from the power supply) and two PCI-E 6 pin connectors on the other end (that plug into the two sockets on the card.
That can't supply enough current to the 6950 card.
Warranty: 2 years
Better power supply models have a three year, five year, or a few have a lifetime, warranty.
Your PS fan may have two sleeve bearings, or one sleeve bearing, one ball bearing, and be more likely to cause you problems sooner than a fan that has two ball bearings or two better bearings
The specs don't specfiy that
If there is printing on the label on the center of the fan you can see from the outside that may say what type of bearings it has . If says ball bearing without an s, it probably has one sleeve bearing, one ball bearing.
If it has two sleeve bearings, or one sleeve bearing, one ball bearing, occaisionally make sure the fan is actually pushing air out of the back of the case where the PS is - the fan may stop spinning eventually and if it does, if you didn't notice that in time, the power supply will overheat and damage itself. If you need to, replace the fan with a case fan that has two ball bearings or better bearings that has three wires connected to a 3 pin plug that you can plug into a spare 3 or 4 pin fan header on the mboard (if you have one) so that you can monitor it's rpm.