black screen on boot up

hello all I have a p5nd2-sli deluxe with intel pentium D 2.80ghz
chipset is nForce4 sli intel edition.
currently running 2 gigs corsair ddr2 (pc2-5300) 333mhz in dual channel.

I just purchased 2 gigs corsair ddr2 (pc2-6400) 800mhz, that i wanted to add to my other 2
slots that were empty, bringing me up to 4 gigs total. I know under windows xp, my system
shouldn't recognize the full 4 gigs. I went along with it anyway, as i will be upgrading to vista in the near future.

After installing the other 2 gigs, I booted up and checked the bios, and checked system installed memory, and it read out at 4 gigs. So it was looking good, i closed bios and proceeded to normal startup. Then my system just kinda froze, the windows xp logo never came up, just sat there on the black screen. So i took the new ram out, and problem goes away.

I just tried taking out my old ram completely, and putting in just the new pair in their respective slots to run dual channel. I get the same problem. Does my motherboard not support this or something? or is the ram defective? Can anyone shed some light on my problem?

(i'm not exactly super acknowledged in pc hardware, so any help most appreciated)


this is the exact ram i purchased
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

can someone verify that this is compatiable with my mobo?