Need some help with SLI

[Darkhate]

I am having a little trouble getting two new 7900gt's to work together in SLI

when I go and look in the Nvidia properties it only says 256mb when it should be 512mb right

So can anyone help me out

thanks for any help

[CanaBalistic]

You have the jumper installed?
Updated drivers?
Checked settings?
Proper power connections?

[Darkhate]

Both My Videocards and my motherboard supports SLI

I have 2 x

XFX GeForce 7900 GT EXTREME (520MHz) 256MB GDDR3 PCI Express x16 Video Cards

My motherboard

ASUS A8N32-SLI Deluxe Socket 939 NVIDIA nForce SPP 100 ATX AMD Motherboard


I have update everything and still no luck
or does it suppost only show 256

Videocard driver is 84.21