HIPER (High Performance Group) was founded in Milton Keynes/UK in 2001.
CWT (Channel Well Technolog(y/ies)) is the main OEM of its PSUs. Andyson, Sirtec and Seventeam are some of the other OEMs that were used.
HIPER is now out of business and there is no way to contact them for RMA of their products.
The Hiper Type R 580W (HPU-4B580) provides 20 Amps on the +12V1 rail and 18 Amps on the +12V2 rail with a max combined of 360W (30 Amps).
The NVIDIA GeForce 8800 GT graphics card, when running at stock speeds, will draw a maximum of 8.75 Amps from the +12 Volt rail(s).
Your current power supply is more than capable of meeting your current system requirements.
During the motherboard's power on self test do you hear a single beep? Do you see anything on the monitor at all?
Is the graphics card fully seated in the PCI Express slot?
Have you tried the graphics card in another system to prove that it works?