Xfx gefroce LOWERS system ram upon install!

rfp1412

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Aug 14, 2009
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Ok, I just installed 2 xfx geforce 9500gt's (512ddr3). I run 4 monitors. I have 4 gig corsair xms3 ddr3 ram. It's 2x 2gig sticks dual channel 1333mhz. intel dp45sg mobo. windows xp pro. Upon install of the first card, I get 2.99 ram in windows system manager window. After installing the second video card, I get 1.99 gb of ram! What happened? The mobo has NO onboard video. I can't figure this one out! Video cards eat my ram i guess? How can I get this back to 2.99 at least? why would this happen? Thanks!
 

rfp1412

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oh yeah, i more thing, the mobo has 2 PCIe 2.0 slots, these cards are PCIe 2.0 cards. When In the BIOS with only one video card, it says 16x, when I put in the second card, it says 8x for each card. Thanks again.
 

Noobster15

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Ok heres the deal, because the video cards have RAM of their own, the system doesnt have to use as much of its RAM. (On motherboard)

Also because of the graphics cards Windows will read that there is lower system RAM then there actually is installed.

Calm down, your not losing any performance.
 
Actually, you will lose performance. The reason that the RAM is dropping is because you are using a 32 bit OS. As long as you use a 32 bit OS, you have a maximum of 4GB of address space, and video cards will eat into that. After all of the space needed for your other hardware is removed, the remainder will be the amount of RAM you will be able to see. In your case, as far as the OS is concerned, you only have 2 gigs of RAM. The solution is simply to get Windows Vista or Windows 7 x64, which have vastly more addressing capability than is required for any modern system, and which will be able to address all 4 gigs of RAM plus all devices without conflict. You could also use XP x64, but it was never very common, and drivers can be an issue.
 
Agreed with above.

A 32-bit OS can only address 2^32 (4GB) of Address Space for all devices the PC uses. Any device that is used will start to eat into that 4GB amount.

Generally:

4GB - 512MB (Motherboard) - (Total GPU RAM) - (Other Devices)

In your case: 4GB - 512MB - (512MB (GPU 1) - 512MB (GPU 2)) = 2.5GB.

I'm not sure why you lost 1GB instead of just 512MB when installing the second card; this might have something to do with how SLI addresses RAM.
 

rfp1412

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Yeah that's kinda what I figured.... I'll consider switching to vista, but am I better off with 2gigs in xp, or 4 in vista? I've heard so many bad things about vista, slow, needs 4 gigs just to run good, many errors, all kinds of stuff. Is this still the case? I have no vista experience, simply restating what I've heard. Do you guys think I should switch to vista, or keep it the way it is? Thank you very much!
 

carickw

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make sure you get vista with free upgrade to windows 7 (i think they all are now). But usually windows OSes aren't to their "full potential" until SP1, so I would use Vista until 7 gets there.
 
Alternatively, you can go to Windows 7 x64 - The release candidate is still available through Microsoft (for a few more days, anyhow), it's free, and will last until May 2010 before it time bombs and forces you to buy a real licence.