Shuttle AK31 v3.1 w/ Athlon XP 1900+ instability @ 140+ fsb

With my new Athlon XP 1900+ and Shuttle AK31 v3.1 at 143 x 12 (default multiplier) and 1.8 vcore, i will get crashing in 3d games or an occasional random reboot in windows (Windows 2000). Temps are 33C at idle, 35C under full load. Prime 95 runs flawlessly, no problems with that benchmark. No overheating is occuring. memory settings are set for maximum performance, cas 2, 2, 5, 2, 4, 1, 1. I will not settle for any less memory performance. At 140 fsb everything works fine, no crashing. So what i am asking, what seems to be the problem? lack of voltage? i doubt the memory settings are too harsh for the crucial DDR (@ 2.7 volts). And i know all my PCI cards can handle that fsb because they have done better on a different mobo/cpu. My +3.3 volt is only at 3.34. I know the default on most boards is around 3.4 and sometimes 3.5 . On my previous asus motherboard i could adjust the +3.3 volt with a jumper, but i guess the shuttle board does not allow this? Need some help as to what could be causing the crashing.

This may sound crazy but you may need more power. 27 fans and SCSI, that is sucking up some power. Have you ever thougt to run 2 PSU's? I doubt it is the mobo or the ram, both are proven high overclockers. Could be the CPU but seems like you are drawing some serious power. Also try with only 1 stick of ram.

There's a chance that youre CPU is hitting its limits. 140x12.5= 1750 Mhz. Those chips are running pretty fast already at their stock speed.

Actually they are only running at a multiplier of 12 at stock speed. Their stock speed is 1600 Mhz, i am only running it at 1680 Mhz. I think I just need to burn it in, maybe i will start to inch my way up back to 143 fsb within the next few days and see what happens. I don't want to make the voltage go over 1.9 as it dramatically reduces the life of the cpu.

the 166fsb is stable for me.
10.5*166 on 1600+ on ak31 rev3.1

luie said:

the 166fsb is stable for me.
10.5*166 on 1600+ on ak31 rev3.1

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Oh man. That's a sweet OC. You've got a really good chip there. I'm getting a 1700+ on Friday. I'll be happy if I can get it to do 150x11 for 1650 Mhz.

good luck, alex99

Luie