a8n-sli prem
seagate 300gb hd sata
BFG 7900GTX OC
4800+x2
2gb cosair ram
pioneer 8x dvd

i had just bought this sys and was just gonna use the psu with case i got
its a 430w. when i looked on the net it was saying all this stuff about power comsumchen and haveing a big psu if so can someone guide my to the answer

The only reason you may need another power supply is the motherboard you purchased is an SLI M/B, if you plan on going SLI [dual video cards] and the P/S you have doesn't support SLI setups, or have all the M/B connections you may need, then you would need another P/S, but for your listed setup 430w is sufficient.

what if planing on puting a big water water cooling system in

You may need to buy a more powerful PSU.

Here's a breakdown of your PC power consumption:

Athlon 64 X2 4800+ (not overclocked)...................96w
GeForce 7900GTX (non overclocked)..........................95w
Motherbaord............................................20w
2 Sticks of RAM.......................................10w
Hard Drive..............................................20w
DVD Drive..............................................15w
Case Fans (assuming 2)...........................10w

Total Power Consumption @ 100% Load...266w

Estimated max load while gaming............250w

Chech the 12v rails, the typical modern PSU has at least 2 of them. Add up the amps on the 12v rails. If the total is less than 24 amps then I suggest you buy an new one. If you are going to overclock then you definitely need a more powerful PSU.

Sorry, I don't know anything about watercooling.

hmm, by any change a 430w NeoHE?

if so thats a pretty good PSU u will be fine

Yes, the NeoHE 430 can provide up to 384w on the three 12v rails.

However, I am still reluctant to recommend it because of the problems the previous versions had with Asus motherboards. Yes, a new revision has been released in Febraury that resolves the issue. But it is still possible that older revisions are still sitting in warehouses waiting to be shipped.

The OP wants the Asus A8N-SLI Premium.

for you actual system specs, there's no need to buy a new PSU, but if you're planning to do some OC or to use SLI, than you should consider to buy a new, brand-name PSU (Antec, Vantec, Ermax, ACRyan, Sharkoon,etc). As much as I know, a water cooling device doesn't cosume a lot of power, maybe something about 15W (max). Someone who use this kind of cooling could provide you more information

Yeah, a water cooling system definitely wouldn't consume enough wattage to put stress on a 430W PSU if you're only talking about the other components consuming 250W.