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A7N8X-E Deluxe crashes on boot in nv_agp.sys with > 2GB


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I've been trying to upgrade the RAM in my system to 3GB, so I bought 3 Corsair 1GB sticks (3 x CMX1024-3200C2P2) and put them in. Any two of the sticks will work fine, but as soon as I put in the 3rd, my system will no longer boot.


The system (Windows) consistently boots up to the point of loading ACPITABL.DAT, but then hangs or reboots at that point. I attached a kernel de-bug-ger and determined that it is crashing in nv_agp.sys, with IRQ_NOT_LESS_OR_EQUAL.


I've tried working with 2 versions of nv_agp.sys, the latest nForce2 driver from the 5.1 install on nvidia, which dates back to 2004 and provides the 4.3.6 version of the "nForce2 AGP Host to PCI Bridge", or the default driver installed by windows, which dates back to 2003. If I delete the nv_agp.sys driver completely (such that I am condemned to vga), the system boots fine with 3GB. As soon as the system installs an AGP bridge driver, though, the crashing returns.


Perhaps it is an address space issue. I've noticed that the bridge takes assignments of every address from 3GB up to 4GB, and that seems risky, depending on how physicall addresses are assigned to the RAM. I've also tried running with 2.25GB, and the same thing happens. Any amount over 2GB causes the crash.


I've tried all the memory configurations listed in this thread: http://www.houseofhelp.com/forums/showthread.php?t=59728&highlight=a7n8x-e

I've also tried SPD and other conservative settings. It seems to influence whether the system crashes or crashes and reboots, but that's about it.



Has anyone gotten 3GB to work with this board? What else can I try?


Note: to boot successfully with the 3GB installed, I merely need to give windows the /MAXMEM=2048 boot switch. Then it uses only 2GB and it works fine. If I give it even as low as /MAXMEM=2070, it crashes.


Any help or information would be greatly appreciated.






Board: A7N8X-E Deluxe

CPU: AMD Athlon XP 2800+

RAM: 3 x (1GB) CMX1024-3200C2P2

OS: Windows Server 2003

Vid: PNY GeForce 6600 256MB

BIOS: 1013

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BIOS Settings:


CPU External Clock - 166

CPU Mult - 12.5x

SDRAM CAS Latency: 2.5T

SDRAM RAS to CAS Delay (tRCD): 3T

SDRAM Row Precharge (tRP): 3T

SDRAM Active to Precharge Delay (tRAS): 7T

AGP Aperature - 128 MB


I'm going with mostly Auto/Optimal settings here.


I have not tried memtest yet. I had the silly impression I couldn't do that if I couldn't boot windows. I will run it now.


FYI, I just tried installing Windows XP SP2, and IT WORKS. But Windows Server (which I actually need) still doesn't boot. I've previously tried a from-scratch installation of Windows Server, and it runs into the same problem at the same place as my existing installation.

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  • Corsair Employees
After looking at some previous notes, it is probably better if you run 2 x 1GB on this motherboard. First most of these 3 slot dual channel mobos have issues when occupying all three slots. Second you will get better performance with 2 vs 3 since running 2 is the only way to get true dual channel performance(installed in either slots 1/3 or 2/3.
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