Guys, I finally got a twin turbo for my 6990 and it is indeed amazing. I've been trying to over clock it past 880 and 1250 but Im using 3D mark and everything seems to crash. If it doesnt crash before it completely freezes the computer after skippping the first video. Im at 20% pcs and at a regular 1175 on voltage. Should I go up in voltage before trying to go up on the clocks?? Also this only seems to happen to 3Dmark and not any other games I play like D3 Skyrim an deadspace. Thanks in advance.