Low fps while recording

Hello, i have problem while recording battlefield 3 MP, I have Asus GTX 660TI, FX-8320, 8GB ram, WIn 7, 64-bit, and fps is about 45-100+. And then i press record button with fraps it drops to 25-55, and with dxtory to 40-70(but recording fps is about 19-35) So there is a problem i have HDD 6Gb/s

the cable may be sata3, but your HDD is probably not running at 6Gb/s. also, are you recording on a seperate HDD or the same where you keep all your crap installed (games, windows ect.). a seperate HDD drasticly increases performance when recording... ;) I'm assuming you have no SSD.