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My tower just randomly restarts or shuts down. I took it to a certified Apple repair and they said nothing was wrong with it, however the problem persists. I did have them professionally clean the inside because I noticed the fan would come on stay on after a certain point. It’s also well ventilated. If I do not use the computer for days, it will work fine for a while. However if I use it consecutive days, the problem appears and happens more frequently. I spent $700 having the “repair” place clean it and tell me nothing was wrong. Please advise.

There is software that shuts down, and boots up your computer automagically. Look at what applications launch at startup.. Some possibilities: - System Preferences Energy Saver. Cache cleaning, anti-virus or backup software. If this Answer is helpful please remember to return and mark it Accepted.

For anyone having this issue : Shut down. Pull out both RAM drawers. Remove all RAM. Remove all dust (preferably by dry compressed air). Carefully but firmly re-seat the RAM on the drawers. Re-seat the RAM-drawers in your Mac Pro. I’ve had this random shut-down issue right around the time Steve died, so it could also be related to his reality distortion field energy playing havoc on my Mac Pro … but somehow I doubt it ;-) (The restart occurs after an unscheduled shutdown, if you have automatic restarts enabled in the Energy Saver preference panel.)

I’ve had fourof these in now with the same issue including one of my own. I would get random reboots. The frequency increased as the months went on. I tried the RAM, hard drive, replaced video card. It wasn’t until I replaced the power supply that the problem ceased, on all four machines. Mac Pro First Generation Power Supply Unit Replacement

I’ve had this issue for some time. I tried everything from RAM tests, disassembly and cleaning, replace the power supply, logic board etc. I finally decided to pull the heat sinks from the CPU’s. I believe I have finally found the issue which is there are failing capacitors on the CPU card. There is evidence of leakage on the board. I’ve ordered replacement capacitors and will be replacing all the little canned caps.

Having a similar problem, system freezes and reboots. It seems that one of the RAM cards failed. I removed it but one of the processors and one bank of RAM are getting very hot. Not sure what to do about that.

I have this problem as well….I have a Panic Report from my mac. It may point to Eset but Im unsure. If the mac is active, I dont see the issue happening…it goes down when idle and just reboots by itself.

Hey everybody, not sure if this will help anybody, but i recently got a mac pro 3,1 that randomly restarts with the fans at full blast or just goes into a full blast mode. well i tried everything, stripping it down to its bare components and eventually just replace the thermal paste on both cpus as well as the chip to the right of the cpus and voila! it works perfectly. i am writing this paragraph on it now and it has surpassed the time that it will take to go into full blast mode. hope this helps someone!