New graphics card problem

i just bough 2 7900 GTX cards ... i currently have 2 6600 Gt cards... i shouldnt need to delete my current driver since its the same one from nvidia but i did anyway... i plug in the 2 new cards it goes threw the system check no windows splash screen never boots up .... ive tried it in safe mode same thing... ive reseated them and all that they are hooked up to the power supply wich is 480 w not sure if thats to low but i would htink it would be enough to at least get windows to boot up? also the power cord from the cards is 2 female so i bought 2 1 male 2 female adapters and basecially hooked up each card to 1 male of the power supply ... would that be sufficiant? .... really dont know why windows isnt booting up with these cards ( also have tried to just use one and same thing) any ideas or solutions?

 

I'd never use a power splitter for a graphics card, only for case mod components etc. Hard drives, rom drives, and graphics cards should have connectors straight from the power supply. Try it.

 

im also gonna get a 600 w. on my way home from work ...... think maybe 480 to low for them cards?

 

I don't think 480W is too low, it should be able to power them both.

What are your system specs?