I have a really nice Compaq ML350G2 that I use as a Ubuntu LAMP server - 2x1.3Ghz cpu, RAID, etc. Works great except for the fan noise which is insane. I purchased and installed a high-quality Silenx IXP-74-11 fan which is truly whisper quiet. The problem is that 30 seconds into the boot, the motherboard/bios reports a fan failure and reboots. There is a status LED on the motherboard and it indicates a fan failure, though the fan is turning. This is a three wire fan and does provide a RPM signal.
I don't know what the mainboard/BIOS is looking at to determine an error.
Is the fan too slow? It turns 1100RPM at 12v. I think the OE fan is faster.
Is there some other kind of Compaq-specific magic going on?
Thanks for any insight.