Rambus RDRAM PC800 Question

[dbryantlci]

Hi There,
I am trying to squeeze extra life out of an old Dell Dimension 8200 and have run into difficulty with adding new memory (good old obsolete RDRAM)

System details:

Intel Pentium4 1.7GHz, 850 chipset
400MHz FSB
current memory: 4x128MB PC800 RDRAM; 2 x 128MB 45ns Samsung non-ECC, 2 x 128MB 40ns Samsung non-ECC (4 slots total)
motherboard: 00f141 (??)

I purchased 2x512MB Samsung PC800 45ns ECC RDRAM. If I understand correctly, this chipset can work with non-ECC and ECC RDRAM (will disable ECC if mixed), and 40ns or 45ns speed (will default to slower speed).

I had to try different configurations to get this to boot with the new 2x512MB replacing one pair of 128MB's. This did not work well, so I updated BIOS to A09 (latest version), and was able to get computer to boot with 2x128MB in slots 1/2, 2x512MB in slots 3/4. BIOS showed 1280MB RDRAM, as expected. However, when Windows XP booted, started getting strange errors, spontaneous reboots initially, then messages about programs crashing, then a message on boot up about needing to validate windows. Also, once or twice it gave a memory read error at location FFFFFFF or something (not sure), and would reduce available RDRAM (this would not happen every time). I figured memory errors must be doing BAD things to my system, so backed off, put old memory 4x128MB back in. After an error or two, this settled back down to work as usual (which is slow).

I downloaded memtest86+ to test the RDRAM memory. The 4x128MB passed two full loops of tests. When I again installed the 2x512MB in slots 3/4 and ran memtest86+, I got massive errors--essentially it looked like anything sent to memory 1-256MB was OK, but anything sent to memory 257MB and up gave an error. I guess I would not expect bad memory to give ALL errors.

So the question is, is this memory bad, or not compatible? One curious thing I noted is that on memtest86+ the FSB speed is listed as 99MHz, not 400MHz. Is this because of Intel's 4x mutiplier, or could something be wrong with the motherboard/settings? I could not find anywhere in BIOS to change this (BIOS says 400MHz).

Since I bought this on ebay, I can exchange it, but might have difficulty getting a refund. So I'm hoping it's just bad memory.

Any thoughts would be greatly appreciated!!!

 

[Keitero]

Have you tried running just the two sticks of 512MB to see if they pass memtest? The issue with Rambus is that you can't single out a bad stick of a pair unless you have another stick of the same size and speed lying around. If they pass memtest, then it just might be a compatibility issue.

 

[dbryantlci]

Thanks Keitero, I guess I should have thought to do this to be thorough

I tried testing the memory on it's own (2x512MB in slots 1/2, continuity RIMMs in 3/4) and it won't boot. I get a 5-1-2-3 beep code, which if my search was accurate, means memory read/write failure. Combined with the memtest result above (2x128MB in slots 1/2, 2x512 in 3/4 --> massive errors in memory 257MB and above, nothing below), I'm increasingly thinking the memory (one or both 512's) is bad.

Any other thoughts?

 

[mpilchfamily]

Good possibility that its bad. If one RD DIMM is bad then you might as well call them both bad since they have to be paired. Looks like its time to give that old Dell the boot.

 

[dbryantlci]

I am returning the modules to the seller for replacement. I'll post again to let you know how it works out.

So far no "fatal" damage to my system...