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XP + 2gb System + 2gb Video = stupid?

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LiquidArrogance

Member
Joined
Nov 16, 2009
So I knew XP only supported 3 or so gigs of ram, but I guess I didn't know this included video ram.

I recenty installed two 250 GTS 1gb in SLI, an I already have two gigs of system ram.

I was thinking about adding a third gig of system ram, but then read somewhere that te memory cap includes video ram.

So is my current setup actually hindering perormance?

And, obviously adding a third gig of system ram would be useless if not a further hinderance, correct?
 

MattNo5ss

5up3r m0d3r4t0r
Joined
Aug 11, 2008
The memory on SLI'd cards isn't added together. Both cores are used but the GPU memory stays 1GB.

So as of now you have 2GB RAM and 1GB vRAM for a total of 3GB. So, you do have room for more RAM.
 

Daddyjaxx

Member
Joined
Jan 5, 2005
Location
Ormond Beach, FL.
XP 64 bit is not an official O/S...never has been. You will find 64 bit drivers and software that will not run on XP 64 bit that run fine in Vista and Windows 7 64. XP 64 was nothing but a test O/S.

Until you turn on SLI, your memory could read lower when the cards are running as individual cards.
 

iceage

Member
Joined
Oct 23, 2004
Location
Charlotte, NC
To follow up on the OP, do you think Vista would be a better alternative than XP32 if:

4Gb RAM
2x GTX 260 w/ 896Mb RAM
----------------------------
~6Gb RAM total

(and taking in to account Vista's added resource demands)

I know, I know....go Win 7. I've thought about going with the $30 Win 7 Pro version, but haven't pulled the trigger. I fear change. :D
 
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MattNo5ss

5up3r m0d3r4t0r
Joined
Aug 11, 2008
To follow up on the OP, do you think Vista would be a better alternative than XP32 if:

4Gb RAM
2x GTX 260 w/ 896Mb RAM
----------------------------
~6Gb RAM total

I'm assuming the 2 GTX260s are in SLI. If so, the memory isn't added to equal 1792MB RAM, it stays at 896MB.
 

MattNo5ss

5up3r m0d3r4t0r
Joined
Aug 11, 2008
Good question about SLI. They're not. I use them for folding and gaming. When I game 1 GTX 260 is enough power.

Gotcha, just ignore me then...:rolleyes:

Seriously though, get Win7 Pro x64 for $30 from www.win741.com; I did and everything went smoothly. It's a deal you can't beat and it will be gone on Jan 3.
 

MattNo5ss

5up3r m0d3r4t0r
Joined
Aug 11, 2008
Technically, all the memory is used, but not all 2GB at once. The first GTS250 (1GB) renders one frame/line and then the other GTS250 (1GB) renders the next frame/line and so on. So, 2GB cannot be used at one time, it just alternates between which 1GB is used.
 
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hansen

Member
Joined
Oct 26, 2007
Yes, the card will make sure all ram is used, but not all the vram is directly mapped into the cpu's address space. The usual amount is 256MB per core.
 

Neuromancer

Member
Joined
Oct 11, 2005
Location
Tau'ri
I'm assuming the 2 GTX260s are in SLI. If so, the memory isn't added to equal 1792MB RAM, it stays at 896MB.

It still counts towards the 4GB addresable space. The driver tells windows to see the vram as "one unit" but that happens AFTER memory has been addressed (if its not addressed it cant be used so it would be like one card having no vram. the PCIE bus would become a hugh bottleneck in that situation)

I have not run dual gpu in a while, but if you have 2 512MB VRAM cards windows see less than 3GB of physical memory accessible. two gpu or DUAL gpu (CF/SLI) setup.

All memory in the PC counts towards max addressable limits.
 
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MattNo5ss

5up3r m0d3r4t0r
Joined
Aug 11, 2008
It still counts towards the 4GB addresable space. The driver tells windows to see the vram as "one unit" but that happens AFTER memory has been addressed (if its not addressed it cant be used so it would be like one card having no vram. the PCIE bus would become a hugh bottleneck in that situation)

I have not run dual gpu in a while, but if you have 2 512MB VRAM cards windows see less than 3GB of physical memory accessible. two gpu or DUAL gpu (CF/SLI) setup.

All memory in the PC counts towards max addressable limits.

Good to know, I thought since only half would be used at one time, then only half would be counted. I like how everyone is adding what they know, we have a good vRAM + RAM thread goin.