I recently bought a evga 7800gs CO 256mb agp from tigerdirect. When ever I try to overclock it even by 1 mhz the test fails I even tried to to underclock it and the test failed can some one help me? Also on the box and the tiger website it says its memory clock 1300mhz but its default settings are 650mhz. I am using rivatuner to overclock by the way and I am using the 94.24 drivers.