Hope someone out there can help me with a mystery problem on my home computer.

I had a Soyo KT266 Dragon+ with a Athlon 1900+ and 1x PNY 512MB of PC2100 and 1x PNY 256MB of PC2100 (W2K SP4 OS). The system had problems with spontaneous restarts (triggered in W2K and producing dump files). These problems got much worse if a third PC2100 chip was added to the system. Eventually, I was told by Soyo that the board would not support a 3rd PC2100 chip.

This led to my purchase of a Soyu KT333 Dragon Ultra to get support of 3 PC2100 chips. I also purchased 2 new Crucial 512MB PC2100 chips that were on Soyo's recommended list. After replacing the MB and the memory, I reinstalled the OS and all necessary software from scratch. While trying to use the system with the 3x 512MB PC2100 chips, I still ran into frequent restarts. Removal of the PNY chip lessened the problem. However, in processor and memory intensive applications (CAD), the computer still has errors and periodically freezes up entirely (both are generally repeatable). The software that I am running is pretty mainstream and well-supported (although I also have a request in to them regarding the problem).

An overnight memory scan indicated no problems with the memory. Using the CPU Stability Test 5.0 triggered a restart (with dump) last night. All of this seems to point to a CPU issue, but I've always heard that a bad CPU is a rare event, so I wanted to see if anyone had any other suggestions.

Thanks,
Torrey

Sorry mate I dunno what could be the problem. Off the top of my head, are you sure the Soyo KT333 Dragon Ultra suports 1.5GBs of RAM? (even tho it doesnt sould like a RAM problemo to me). It may only support upto 1GB Because if it still supports 3 dimms of RAM, you'd have to have less RAM on each stick, therefor not going over the MAX limit...Tho if you did go over (question for Phanty, Nic, or acid.....) would it just use the max amount of ram the mobo supports, and just leave the rest alone?

Sorry for not being much help, but theres some really smart guys around here and im sure you'll get a solution Or at least some ideas

check for like modules

make sure the read on the physical wafer itself, has the same nanosecond timings..........if, by some reason the chips are not identical, you will experience compatibility issues
oh, nd , if the cpu is the culprit, make sure that the bios is set correctly at HCLK and not spd or hclk+33, or something like that.....confirm that a 266 fsb comes up on your dram timings in the boot screen

Thanks for the thoughts. As to the amount of memory supported, the manual claims support for 3GB, so I shouldn't be pushing it with 1.5GB. The 2 512MB DIMMs that are currently installed are identical so I don't expect any problems with compatibility. I did go into the BIOS and fix the CPU FSB and DRAM speeds at 133MHz. That seemed to stabilize the system to the point of not crashing on a CPU stability test. Still have problems with the 3rd DIMM though. May be time to buy a new CPU.

If the system is stabalized with the two crucial DIMMS & you get errors when you add the PNY one, I'd say that memory module is defective.

Install that module by itself & try running your memory test program.

The 3rd memory module was a new Cruical module that I'd purchased to match the other two (I've cycled through a number or memory modules in various configs and the problem keeps cropping up). Unfortunately, the instability seems to be popping up even with just the 2 modules now. I'm going to replace the CPU and power supply and see what happens. This should give me essentially a new computer. If this doesn't work, I'm at a loss . . .

I had an ASUS mobo once, which had similar quirks.
As it turned out, putting the memory in slots 1 and 3
solved the problem.
HTH