Mac Pro 4,1 random shutoffs

I have been on the apple site looking this one over. It seems that a few people have had similar issues but there didn't seem to be any resolution to the problem. So here I am on this site to ask the question. First of all, I bought this computer used about 4 mo. ago, i am using mavericks. It shut off for the first time about a month ago I suppose after watching movies for several hrs.- it would not turn back on no matter what I tried. So,the next day after I get home from work, I jiggle to cord in the back and push the start button and...It starts up...At that point I figured that the cord was the culprit....so I switched the power cord and the computer has been working flawlessly for the last month until ..last night..it shutoff and what I thought was a power cord problem is not. I am guessing that it could be an overheating issue at this point- Maybe I should open it up and vacuum out the dust, but maybe someone here has a clue other than that, and I thank you in advance for any thoughts.

Several things come to mind:

1. Power supply acting up and

2. Overheating (as you suspect)

Several of our users have experience with maintenance on Mac Pro machines, so hang on and wait for some more replies.

First suggestion is open her up, remove the gfx card and give it a good clean, and reseat firmly. What card is installed, an ATOI Radeon 5770 or a GT120? Then get out the vacuum cleaner and give it a good blow out, particularly around the front and rear fans. the front fan is on the bottom directly in front of the CPU and heatsinks. Make sure if the hose has a metal end, touch nothing.

The next stepis as chscag suggests the power supply. Replaced one in my Mac Pro, and the cost was about $400.00. Are you getting kp's with the shut down? If so go into the Console Log and post what it says.

I'm pretty sure it is the radeon card. hmmm, not sure what kps mean..sorry.. i will reseat the card at least and vacuum the dust..i will get into the habit of shutting down every night also. Since this has happened only 2 times and then it works the following day, I guess I could live with this shutoff problem..It sure is a good thing that I have an old macbook as backup though... thanks all for the responses.

ATI Radeon HD 4870 512- removal

hi, here is the card info: ATI Radeon HD 4870 512
how can i find out how to remove the graphic card?

romegio said:

hmmm, not sure what kps mean.

Click to expand...

"KP's" are kernel panics. This is when the computer freezes up…you get a gray screen and a message on the display in something like 5 different languages…and you are forced to restart.

- Nick

thanks,but i don't think that happens. it just simply turns off,but today i brew it out and it appeared as though some dried leaf and other articles were lodged in the graphics fan...maybe that could affect it? thanks so much for your time

Dried leaves? For sure big time. Keep us posted.

Is this machine being kept outdoors??

i did purchase the computer used and I have no idea how a leaf got into the fan..i will keep my fingers crossed that a leaf was the problem!

With a dried leaf in the gfx fan and watching movies for several hours would sure lead to a shutdown. The thing will be if the card is okay after such overheating. Fingers crossed.

thanks all of you for your thoughts. I just can't imagine how the leaf got in there..it would seem impossible!

Yes it would as intake is directly in front of the CPU heat sink. Have to blow in whilst the machine was open, or one of covers of the slots which are removed to install additional PCI-E cards was left off?