I am using an ancient Q6600 2.4ghz core2quad, and just found out of the BSEL mod, which I believe means Bus Selection mod.
These processors are worth like $10 bucks and mobos around $20, and you can rock a 3.0ghz quad core for ~60 bucks include PSU / RAM / CPU/ MOBO (add $30 for a sexy matx case), + 100-150 graphics card
Thats $200 for a PC that can rock CS:GO at 4:3 max res with decent settings