4870x2 and ram question

[magnerdo]

Hi, I just purchased a 4870x2 to replace my 4870 and I have two problems. First of all, for some reason, my computer only reads 2.6 gigs of ram. With my other card it showed 3.2 or so. Does anyone know what would cause this problem and if it even matters?
My second problem is I tried to Crossfire the 4870x2 and 4870 but I get no display. I might not be installing it right but I tried switching the gpu with each slots and putting the dongle in both ways.

This is my setup
QX6700 2.66 @ 3.47
4 gigs TWIN2X2048-6400C4
P5w dh deluxe
150g wd raptor
1000w silverstone olympia
4870x2
Zalman LQ1000 case

Thanks.

 

[curryj02]

the problem with Xfiring the 4870 and 4870x2 is because the 4870 you have most likely has only 512mb of GDDR5 right? where as your 4870x2 has 1gbx2. so basically, as far as i know you cant crossfire them together, even if you can, you would have to limit your 4870x2 down to 512mbx2. as for why your comp is only reading 2.6 gig im not sure. try running a memtest86 to see if all the RAM is ok.

 

[hallowed_dragon]

What Windows do you have? If you have a 32 bit version of Windows it will only read 3.5gigs of ram that including your card. Try switching to a 64 bit OS.

 

[magnerdo]

I'm using windows xp. The thing is, when I put the 4870 in it see 3.2 gigs. When I use the 4870x2 it only shows 2.6. Also I read that its possible to crossfire the 4870 with the 4870x2 but it'll run with 512 ram. Does it matter how I set up the crossfire? I tried moving the cards to different slots but still doesnt work.

 

[Crashman]

Hi, I just purchased a 4870x2 to replace my 4870 and I have two problems. First of all, for some reason, my computer only reads 2.6 gigs of ram. With my other card it showed 3.2 or so. Does anyone know what would cause this problem and if it even matters?

You already knew why it was showing 3.2GB with the old card right? And yet you can't figure out why it shows even less with the new card? The new card has more RAM, so the system is reserving more RAM for remapping of graphics memory.

 

[magnerdo]

Oh ok. So this is normal? Is it going to have any effect on performance? If I upgrade to a 64bit OS will it utilize all my ram?

 

[lameness]

Yes its normal, yes it will effect performance, yes a 64bit 0S will give you back your lost memory.

 

[magnerdo]

Cool, thanks for the replies.
What about Crossfiring, does anyone know why my computer fails to boot when I use both cards?

 

[magnerdo]

Ok I got my computer to boot with both gpus and the dongle in but it doesnt detect the 4870, only the 4870x2. So I cant enable crossfire. I removed the old drivers and reinstalled a few times too and still doesnt work.
Any know whats wrong?