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.

1100 rpm is too slow.

this is a SERVER, not a PC. if you don't use the proprietary equipment in it, it detects failures in that equipment, and acts accordingly.

exactly

servers arent designed to be quiet anyway. They are designed to be cool so they can run 24/7

Ive got an old proliant 1600 (dual pentium 2 lol) and it sounds like a damn jet taking off, but it has never overheated.