It's an additional 12V connector for power-hungry CPUs. It's located near the CPU to keep the motherboard traces short.
The image is fuzzy because it's a jpeg and there are a lot of compression artifacts visible around the text.
On some power supplies, what appears to be a 24-pin plug is actually a 20-pin plus 4-pin that lock together. Do you think that may be true of your supply? Do you have a single spare 4-pin connector or do you have two?
Anyway, you can work out where your plug is supposed to go because pins 11,12,23,24 are keyed the opposite way to the CPU power connector.
Last edited by Bushfiva; 11th February 2010 at 06:06.