Looking for good GPU stress test program for overclocking HD 5970

System Specifications:
Case: Antec Three Hundred
4 - 40 mm fans
1 - 60 mm fan
1050 Watt X4 ATX power supply
MSI X58 Pro-E mainboard
2.8 GHz Intel Quad Core i7 LGA 1366 CPU 930 overclocked stable 69 degrees celcius loaded 3.61 GHz + 0.08 Volts
Ultra Chilltech Overclocking CPU cooler
4 GB Corsair XMS3 CMT4GX3M2A1600C6 1600 MHz 1.64 Volts with dual cooling fans memory
Pioneer BD-RW BDR 205 ATA Blu Ray Burner drive
AVerMedia C027 PCIe HDTV tuner card
WDC WD20EARS-00J2GB0 2 Terabyte SATA hard drive
WDC WD20EARS-00S8B1 2 Terabyte SATA hard drive
WDC WD5000-AAKB-00H8A 500 Gigabyte IDE hard drive
ATI Radeon Sapphire HD 5970 2 GB Video Card
Razer Deathadder gaming mouse
Logitech Webcam C160
40 inch Dynex HDTV
Windows 7 64 bit Ultimate Rocks
My intention is to install a water block onto the video card:
EK - Radeon 5970 Water Cooling Block
and run the lines outside the case to a reservoir
When installed, I want to stress test the video card under full load for 10 minutes to determine when temperature reading stays below 69 degrees celcius.
For stress testing my:
2.8 GHz Intel Quad Core i7 LGA 1366 CPU 930
I used used Prime95(a prime number generator) to load and CPUZ(a CPU core temperature monitor) to guage for 10 minutes.
Is there a prime number generator or similiar program for video cards?