RAMBUS question(s)

[Rickover]

Hello All,

I have a PC that uses PC1066 memory. It has 1.5GB in 4 Samsung ECC modules (2x256 + 2x512).

I'm looking for an updated guide showing RIMM population rules for Intel i850e based motherboards using PC1066 memory such as the Asus P4T533-C. The last version of the user's guide for that MoBo (v. 1222) barely mentions 512MB modules.

I know that (for PC1066) the maximum number of devices supported is 48 and that the maximum memory is 1.5GB. And I've figured out by trial and error that the 512MB modules must be loaded in the first slot (nearest the CPU and MCH) in each channel, but I've never seen any published info that states this.

So I am looking for a Intel/Rambus faq. that gets into these details, but doesn't require an engineering degree to understand.

It's not that I haven't tried. I did find the Samsung application note "PC1066 RDRAM Operation with i850e Chipset board" dated Nov. 2002, and Intel document 290691-004 "Intel® 850 Chipset Family: 82850/82850E Memory Controller Hub Datasheet", but even that arcane document doesn't spell it out, or if it does so, I missed it.

Perhaps one of you kind folks knows of a good guide to such matters?

Many thanks!

 

[COLGeek]

What problem (or knowledge void) are you trying to solve (fill)? As RAMBUS is fairly old tech, you aren't likely to find any current info. Please clarify.

 

[Rickover]

Thanks for responding, COLGeek. In essence I am looking for the final, complete guide to RDRAM implementation. As to what problem I am trying to solve... Well, I haven't mentioned that, but since you ask...

I've been running memtest and getting errors. After switching module positions I have arrived at the most error-free configuration for the chips I currently have, but I still get the occasional error. The best performance I have been able to achieve is one error in ten passes of the memtest standard suite. I am trying to track this problem down but can only find limited info on the RDRAM system. I would like to be able to identify which module (or other component) is causing the problem, but because the memory is interleaved I am unsure what to conclude from the data memtest is giving me. In the best configuration the errors occur in test 6 and always near 1140MB. In other configurations I also get errors in test 7 occasionally and those occur around the 700MB range. Swapping modules into other positions gives more errors, but the failing memory addresses are always in the same general area, Iow, moving the modules is not helping me determine which module is at fault.

In a little bit over his head,
Rickover

 

[COLGeek]

I applaud you on trying to increase your technical understanding of RAMBUS, but to solve your problem doesn't require that detailed knowledge.

You have either defective memory or a defective memory controller.

As you know, RAMBUS must be installed in pair. Have you tried to isolate which pair has the problem? Try running memtest on each pair individually to see if you can isolate.

If both pairs pass when tested individually, then you likely have a flaky motherboard (holds the memory controller). If that is the case, you should consider buying a whole new system (mobo, memory, CPU, GPU, etc).

 

[Rickover]

Thanks for the kudos. You are kind, Sir.

Yes, I tested both pairs individually and there were no errors.

Darnitall,
Rickover

 

[COLGeek]

You might be able to find an old "new" mobo via eBay. Regardless, I would strongly suggest new guts for your system. You sell the old RAMBUS to help finance.