When you buy a PSU, you must buy twice as much as you need!

[jcarle]

Not to chime in and come off as arrogant but using wattage as a basis for your arguments is a complete waste of time as it doesn't paint a true picture. Wattage is the sum of voltage times amperage and anyone with some basic math skills knows that in a formula such as x * y = z you can have different values for x, y and still equal the same z.

To quote one of my replies in a previous thread that discusses this same issue:

You have to be careful on how you juge the power supply you need. You need to remember that Watts are a calculation based on Voltage times Amperage (W=V*A). A computer's power supply will generate multiple voltages, which is why they're called Switching Power Supplies. They generate 12V, 5V and 3.3V, all of which add to the wattage. Look at the following to see what the difference can be.

Power Supply 1: 500W

30A * 12V = 360W

25A * 5V = 125W

4.5A * 3.3V = 15W

Power Supply 2: 500W

40A * 12V = 480W

3A * 5V = 15W

1.5A * 3.3V = 5W

Now, the numbers are unrealistic as they do not reflect typical power supply values, but the principal still applies. Both power supply are calculated to be 500W power supplies but the amperage available for each voltage is completely different.

In the parts you list, the 8800 alone is very aggressive on the 12V. A lot of memory can require more 3.3V or 5V, same with the CPU. In general, a large quantity of optical drives and/or hard drives can also strain the 12V and 5V lines. If you want to be on the safe side, get yourself a power supply from a reliable company such as Seasonic and choose one that has an ample quantity of amperage on all rails. A little bit of research and a little bit of time and you will be able to find a power supply that will provide enough amperage in a well balanced fashion to suit your needs. Most of the power supplies in the 500W+ range then to have amperages that suffice all around. If you plan on building yourself a large system, then you'll want to look for something that is in the 70A range on the 12V lines.

Edited July 23, 2008 by jcarle