e6600 underperforming

I have a e6600 that I've had for 2 years now, only recently the performance of it has drastically decreased. I have it OCed to 3.1 ghz which is confirmed by CPU-Z. When I run the windows experience index I get a processor score of 5.1 with everything else around 5.9. The poor performance is also confirmed by playing TF2 which used to run perfectly. Now I get frame rates of 20 fps on 32 player servers not even looking at people. Just looking at the general direction of where people are at through a wall gives me very low frame rates.

I've never had an issue like this before. The only thing I can think of is to take off overclocks and see if I can at least get the regular 2.4 ghz e6600 performance. Anyone have any ideas?
Just yesterday I reformated cause I thought it was a software/vista 64bit issue. Everything is clean on this computer right now.

It feels like it's running at about 1.5 ghz in terms of performance.

memory issues?

I get a 5.9 on the windows experience index for ram. I have tried reseating it and making sure the timings/voltages are correct and they are. I don't think it's the ram even though windows index isn't exactly the best benchmarking tool

Run some SuperPi times - that's the best way to determine if somethin's up.