HI im upgrading soon and buying the core duo 2 e6600 or the e6700 what ram would be best for this set up pc2 many thx

If you have no intentions to overclock your system, all you'll need is DDR2-533 (PC2-4200).

i would be over clocking up to 3.ghz

The E6600 runs at 2.4GHz (9 x 266MHz). To get it to run at 3.0GHz, you'd need to increase the CPU frequency to 333MHz. All you'd need is DDR2-667 (PC2-5300). The E6700 runs at 2.66GHz (10 x 266MHz). To get it to run at 3.0GHz, you'd need to increase the CPU frequency to 300MHz. So once again, all you'd need is DDR2-667 (PC2-5300). You can always get PC2-6400 (DDR2-800) or PC2-8500*** (DDR2-1066), provided you realize that for best performance, you'd have to underclock it. *** AFAIK, there is no PC2-8400

poss go for the pc2 6400 have just bought the e6750 off ebay what would be best for this chip i play alot of online games bf2, ,bf2142, ,arma assault, il-2 ....lol

am i better off getting brand memory or cheap memory pc2 6400 (8000 quite abit of price difference

Dude, you don't HAVE to get PC2-6400! This has been explained dozens of times. On an Intel system, the optimal FSB:DRAM ratio is 1:1. So if the CPU frequency is 266MHz, the RAM frequency should be 266MHz. If the CPU freq is 333MHz, the RAM freq should be 333MHz. PC2-6400 RAM is designed to run at 400MHz. In other words, if you get PC2-6400 for your 266MHz (1066MHz FSB) CPU, you'll have to run it under it's rated speed...even if you overclock! BTW, if you're in the US, RAM is cheap. Have a look at this 2GB (2 x 1GB) PC2-6400 for $65 after rebate: http://www.newegg.com/Product/Produ...