Dell power edge 700 motherboard

Losing all IDE drives at once aounds like a bios problem. First make sure that the IDE ribbon or sata cables arn't loose, then go in to the bios and poke around. Your drives are likely disabled.

I replaced bad IDE drive and now all drives work. However, this is not the main problem it seams, since I've lost the back fan for a second time. This system doesn't have a VRM (voltage regulator module), so I don't know if anyone is aware of why the back fan keeps going out, and if there is a known problem with the mother board causing the back fan to burn out. Any thoughts -anyone? Thanks for kindest response.  

Back fan may be bad. Mother board could be bad too.

If I turn computer on and immediately spin fan with my finger, it will stay running for a while. However the CPU begins to heat up, and system goes into thermal shutdown. On subsequent reboot the screen indicates -Fan not found, and -overheating detected.

This bios does not show temp for System/CPU -simple bios. At this stage I could change the fan AGAIN (although the fan will run with a finger nudge, it may not be spinning fast enough to keep the CPU cool. In any case I'd need a new fan (make that a refurbished fan -new cost more than this used Server.)

As for the Mother board -it's up in the air --could be that the white wire that turns the fan on/off when the CPU gets to a certain hi/lo temperature is not sending signal to the fan to turn on/off. (Then again it could be sending a signal to the fan why the fan rocks back and forth, but won't start until it gets a finger nudge.) Hum... Could be one of the windings in the fan itself is out of spec (burnt out) from overheating. I took the old fan apart and next to one of the windings the PCB was burnt.

See -It could very well be the MB that's bad why I am inclined to changing the MB. Before the fan went out completely. It was in a "race" condition running faster than normal with louder than normal noise. This could indicate a "race" condition with the VR. I checked the output voltage of the VR without load (fan not hooked up) and it read 11.9VDC (12VDC). However under load the VR could be putting out more than 1.5A to the fan to send it wild.

I will get another fan and mother board. I ran across fan for about $35 and MB for about $80. I am curious now to know what the deal is. And I will swap out both fan and MB. This way if the fan goes -I know that the MB is piece of s_ _ _! That's why when DELL built models after mine they went with VRM's that you could replace along with fan.

It will be probably a couple of weeks before I get parts.

Thanks all!!!!!!!!!!!!!