4GB memory on XP Pro

tunerX

How do you get the system to recognize 4GB of memory? I have 4GB installed in a system but it only shows up as 3.5GB.

Drakonblayde

Is the video onboard? if so, it's probably sharing the other half gig

tunerX

I have 8MB on board (ATI Rage XL) and 256MB on a Radeon 9800 AGP card.

Sandra sees 4-1GB dimms and only reports 3.5GB. Windows only reports 3.5. I read that PCI devices are allocated memory and it is unusable by applications but 512MB seems like too much. I need 384MB more and would be willing to sacrifice 128MB to the board.

Drakonblayde

Well, if it's not shared, and the bios reports 4 gigs, you should have 4 gigs, even if the PCI devices are taking up memory, it should report your total properly... hrm....

What motherboard and RAM is it? That's kind of messed up that Sandra would see 4 1 gig dimms and only report 3.5 gigs...

I dunno man, it sounds like one of the sticks is possibly bad, or maybe a bug in the chipset. Have you tried booting them one by one to see if they each report 1 gig?

I mean, I've got a pair of machines running 4 gigs each, and XP and Win2k both show them as 4 gigs, so I doubt it's windows doing any funky math.

tunerX

http://www-1.ibm.com/support/docview.wss?rs=0&uid=psg1MIGR-40247&loc=en_US

I read the above article and figured that this is what must be happening. I was thinking that there must be some way to limit what the OS reserves. I have a rocket raid 8 disk array and 2 quad fast ethernet cards in it. I just can't imagine that the OS would need to reserve that much memory.

I have an IBM se7505vb2 and 4x1gb ECC registered dimms. The bench techs, where I work, have a tester and my memory tests good.

Drakonblayde

You know, from what I remember, the Rocket Raid's don't have their own onboard cache, so it may be stealing some of your system memory for itself. I think that's one of the reasons I ended up passing on it and going for a 3Ware Escalade 9500S-4LP (128 on board, expandable to 256)

Judging from that article, it's mostly the onboard stuff that's going to steal system memory, which has usually been my experience, I don't think I've ever seen an installed PCI card cause my system memory to report incorrectly, but I've certainly seen my onboard sound and video steal it.

I'll go chat with our Intel guys, I'm not sure if we use this board or not, but if so, they might have seen it before.

tunerX

I don't have any pci-x slots. When I was looking for a sata raid card, I wanted maximum IO, so I went with a 133MHz PCI bus. The escalade was nearly 3 times the cost and only ran at 66mhz.

I see now that the escalade can handle up to 1gb of ram. If I would have had a motherboard with pci-x, I would be smacking myself upside the head right now.

Drakonblayde

Erm, I didn't know PCI went to 133mhz without PCI-X hehe

And yeah, 3Ware stuff is expensive, but it's damned nice. My only complaint is that I can't use the management tools under OpenBSD, but that's what I get for running an OS who's management is fanatical about licensing (and I don't know enough to port the FreeBSD driver myself /grumble)

Anyway, I went and had a chat with our Intel guys, and we don't use the board, but they're under the same impression I am, either your RAID card is sucking down your memory, or some of your onboard stuff is.
Half a gig does seem pretty excessive though