Okay, so I ordered a Corsair 500W power supply for my HP P7-1054 and when I started to put the thing in, I realized that I am missing one plug? It's a little 4 hole plug that is on the generic 250W Bestec that came with my computer. Do I need this?
Are the 4 pins arranged in a single row (i.e. 1 x 4) or a square (i.e. 2 x 2)?
Are you talking about the Floppy Diskette Drive 4-pin power connector? It's 1 x 4. If you don't have a floppy diskette drive in your PC then you don't need it. Both of the 500 Watt power supplies that Corsair sells include Floppy Diskette Drive 4-pin power connectors.
If it's 2 x 2:
From Corsair's Frequently Asked Questions:Q: Where’s the 4-pin EPS/ATX 12v connector that I need for my motherboard?A:
Our power supplies ship with an 8-pin connector that splits in half. Use half of this connector for the 4-pin EPS/ATX 12v connector on your motherboard.