|Ok, since no one seemed to have a clue or motive to jump in the thread, I’ll answer my own question, and maybe this will help someone else.|
After installing the new memory the first problems I noticed were crashes in Google Chrome. A page would load and almost immediately crash. On reboot Windows XP (SP3) would call for CHKDSK every time. Windows explorer would crash, or not show any contents in a folder, or would report that a file was corrupted and could not be read/moved/deleted. While I suspected a HDD failure, this HDD was only a couple years old, and had only been used for maybe a year or so. I couldn’t ignore the fact that the problems only started after installing new memory.
So, I developed a schema to test each memory module, (1) one at a time, (2) in combinations, (3) and on each mobo slot. Next, I went back and reconfigured FSB and core/bus ratio on the mobo to match that of the processor, which at the time I thought was an Athlon XP 1800+. The mobo default FSB was set at 100MHz, and when I built the machine I had relied on SPD to detect and set the correct timings.
As it turns out when I reset the FSB to 133MHz and the multiplier to 11.5, the system returned saying I had a 2400+ processor. I also noticed that even though I had manually set the multiplier to 11.5, bios was returning 15x in MSI’s Fuzzy Logic, which is correct on a XP 2400+. I was not trying to overclock the processor, but just set it to it’s nominal speed, and match the speed of memory.
The nagging question was why the machine had been stable even though the original memory failed diagnostics. I recently read an article somewhere about memory timings. Since I had relied on SPD, timings seemed to be nothing more than a topic for discussion, because in the real world those settings were left to firmware. There are four main settings: (1) CAS latency, (2) RAS to CAS delay, (3) RAS precharge, and (4) RAS. I searched the web for the timings of the new modules I had purchased, and found nothing, not even from the manufacturer. Then, I found a program, “System Information for Windows”, that tells just about all you need to know about system software and hardware. And there is was, information about memory speed, supported frequencies, and timings at various MHz. The eureka moment came when I saw that the new modules do not support SPD. The bios was unable to AUTO set the timings.
I started diagnostics again after setting the timings according to the data stored on the module’s EEPROM. First on one, then two, and finally three modules in combination and received no errors. I had set up a 40 GB sacrificial HDD with a copy of Windows XP, and had unwired my main drives in case of another disaster. Everything seems ok, no crashes or instability after about 8 hours, whereas before it was just a matter of a couple of seconds when even the OS would simply crash and restart.
For me it was a lesson that many resellers don’t know diddly-squat about what they are selling, I didn’t know squat about what I was buying, and the limitations of bios and hardware when corners are cut to make a product cheaper. My new memory is working fine, and this old computer is zipping along nicely. But it would have been nice to know beforehand the challenges I had to face.
What I don't know is if the FSB and the multiplier had been set correctly at the outset, would I have had the same problems? I don't know and will leave that to someone else to figure out.