Hammer, several suggestions:
Your CPU is not something on a 64Bit machine that is going to limit your SLI capabilities, however your Powersupply and Memory will.
The need for a quality and high powered PSU is a MUST, espeically if running 2 x 6800GT's. Even a 480W Neo Antec or ThermalTake would be pushing it.
I HIGHLY suggest you get one of these powersupplies:
Antec TruePower 550W PSU (CA-002-AN)
Enermax EG851-AX-VH 660W Power Supply (CA-011-EN)
Enermax Noisetaker 600W EG701AX-VE(W) SFMA Power Supply (CA-013-EN)
They are quite expensive, but to run a AMD64 3500+, an Asus SLI motherboard and 2 6800GT's thats going to consume power like a starved fat man, i cannot stress enough how important this is, if you skimp on a powersupply you WILL damage your system and your components.
Also don't skimp on memory and buy cheap generic memory, or even expensive generic memory, get memory from: Corsair / Kingston / OCZ / Geil / Samsung / Crucial.
As a note on your choice of Dual 6800GT's, I personally, would just buy the one 6800GT, buy a really BEASTY powersupply that you know WONT let you down like the one's mentioned above, get some really NICE memory like:
Crucial Ballistix
OCZ Platinum
Corsair XMS
Kingston HyperX
Geil Ultra
and get the fastest you can, preferably in Dual Channel.
Getting 2 x 6800GT's sounds great, but there really is no point at the moment, no games for atleast another 3-6 months will have proper SLI support, and a 6800GT is going to be more than enough to power ANY high end game at the moment at full graphics, even DOOM3..
And SLI only increases performance by 1.8X that of running 1 graphics card when the game or program is designed and optimised to properly utilise it, and i can guarantee that this wont happen in any games any time soon.
PLEASE PLEASE PLEASE:
DONT SKIMP ON A POWERSUPPLY and DO NOT buy from a make / brand that i have not mentioned.
Same applies to your memory, by buying shity memory of cheap generic memory or generic memory in general you are basically going to bottleneck the performance of such a powerful system.
Those who know best, please back me up on this post!
p.s im only being abit harsh to make sure you get the right thing, what would be worse than buying that awesome system and not making the most out of it? or even worse damaging it..
