Do I need a 24 pin PSU for 7800 GTX

[Pauly]

I am thinking of having a system built with an Asus mobo -model not yet known. There is an upgrade offer of a twin fan 600w PSU, make not shown. I will be wanting to put in a 7800 GTX card,but the builder only offers 7800GT, so i will get the video card (GTX) from another source.
I live in the UK. My present system uses an Antec 550 truepower - 20 pin.
Do I need thePSU to be one of the new 24 pin ATX 2 ones? If so, why as some have said it is not necessary. I think the mobo is NOT a SLI model. I don't intend to SLI.
I want to be sure of my facts when discussing with builder, and at the moment i don't know when a 24 pin PSU is mandatory and when it isn't.
Please advise
Thank you.

 

[Pauly]

Bump please - The supplier has replied that the PSU is NOT a 24pin ATX 2 one. the rest of the deal seems OK. I have asked for the mobo model . Please can someone answer this for me . If the PSU is unsuitable for the 7800GTX, I need to know!
TIA

 

[JPB]

Just get one of these....That is if the motherboard you choose has a 24 pin connector...

http://www.newegg.com/Product/Product.asp?Item=N82E16812145002

 

[ayabe]

I don't believe it's a requirement for the GTX, it really depends on the motherboard you get though. If worse comes to worse you could always buy a 20-->24 pin adapter.