I just got two P3 900 Mhz Xeons for a great price, but SuperMicro doesn't know whether they will work on my S2DGU motherboard. They have tested 700s (which work) but not 900s. They say it will either boot up or not, but I won't damage anything, since the voltages are OK. I will be installing in the middle of next week, but it would be nice to know if anyone else has tried it and what the result was.
Update to my prior post: The PIII 900 MHz Xeons are up and running. I have never before seen WordPerfect 9 load from scratch in only 4 seconds. Seems 2 MB caches do indeed help. Also should note that SuperMicro tech support was exactly that, Super, willing to talk to me about various trials and tribulations and to help me understand the significance of the microcode update in the BIOS (not yet done for the 900s by SuperMicro on this discontinued mobo, but they said they would try to get it out of AMI!).
You all recall the famous math error in the early Pentium (586) chips? Seems now that when Intel issues a new processor, it publishes a white paper on the errata (small errors) on the chip, and the BIOS makers put microcode in the BIOS to get around the errata.
Fortunately, there are few errata for the 900s (finally released at the end of August), and I'm not sure how likely I am to run into them. Getting a lot of Blue Screens of with exception 9C (hardware) with the new processors, but I also got them when I was running the PII 450 MHz 512Kb cache Xeons, though maybe not quite so frequently.