8800gtx graphics card glitches driving me barmy!

Greetings all - bought an XFX 8800 gtx from overclockers and for a week or two it worked ok. Then glitches started appearing on screen and as time moves on more are appearing. I think one or both of the 6pin PCIe power leads going to the 650w Tagen power supply are in trouble but cannot for the life of me find where to buy them on the internet!!

When the HDD is being hammered these flicker and sometimes dissapear for a second. When the HDD is not being hammered they come back. There not there at the BIOS and flicking the screen upside down sends the glitches upside down too so its not the monitor.

Overclockers not replying to my e-mails so just need somewhere to buy 2 x 6pin PCIe power leads to try them out. (Not the 6 pin to 4 pin convertors as XFX specifically state NOT to use these)

Any imput much appriciated as using the computer is becoming a nightmare!

Thanks