Problems with GV-NX88T512HP rev 1

I recently bought a Gigabyte 8800GT graphics card GV-NX88512HP rev 1 and within a few days of operation the computer started lock up with a pink screen. The only way to recover was to reboot the system. I have not altered the card in any way as it is already factory overclocked to 700Mhz. They appeared to have this problem with the original version of this card and subsequently changed several parts including swopping the Zalman V700 heatsink and fan for a V830. When I contacted Gigabyte techinical support they advised me to turn down the Core Clock to 600Mhz while they investigate the problem. My knowledge of graphics cards is limited but I chose rivatuner to try an accommodate their request. However, when I initially ran rivatuner before making any adjustments the following factory settings where displayed:

$ffffffffff ----------------------------------------------------------------
$ffffffffff NVIDIA specific display adapter information
$ffffffffff ----------------------------------------------------------------
$0100000000 Graphics core : G92 revision A2 (112sp)
$0100000001 Hardwired ID : 0610 (ROM strapped to 0611)
$0100000002 Memory bus : 256-bit
$0100000003 Memory type : DDR3 (RAM configuration 00)
$0100000004 Memory amount : 524288KB
$0100000100 Core clock domain 0 : 450.000MHz
$0100000101 Core clock domain 1 : 1188.000MHz
$0100000006 Memory clock : 702.000MHz (1404.000MHz effective)
$0100000007 Reference clock : 27.000MHz

It looks to me as if the factory setting of this card were already set at 450Mhz and not 700Mhz as advertised. Am I misreading this or has Gigabyte delivered a batch of underpowered 8800GT cards that still don't work? Any help would be appreciated.