Mac restarts itself at random

This has been happening for about a month. Everything will freeze just before the screen turns black and then it restarts. After it reopens it will, on occasion, ask me for my password other times it goes back to the desktop but all the programs are closed. I felt there was some connection between the restarts and Thunderbird so I have been quitting Thunderbird. It may of gotten better but tonight just as it froze, the images on the screen started jiggling and the curser started jumping around. I was able to move the curser enough that I just shut it down.

Does anyone have any advise as what my first step(s) in correcting the issue might be?

Thanks
L

Waterdog said:

Does anyone have any advise as what my first step(s) in correcting the issue might be?

Click to expand...

Just so we know...what model "Mac" do you have (be as detailed as possible)...and what OS version is it running?

- Nick

I have a 20" desktop, originally bought with Tiger (?) but I upgraded to Snow Leopard several years ago. Currently running 10.6.8 on a 2.16 GHz Intel Core 2 Duo. I am only using 32GB. Apple replaced my hard drive a couple of years ago. I think on account of a recall.

Waterdog said:

I have a 20" desktop...

Currently running 10.6.8 on a 2.16 GHz Intel Core 2 Duo.

Click to expand...

Thanks for the info...I'm assuming we are talking about a 20" iMac.

When the computer "restarts itself" does it:

- Show a black screen with a bunch of text in multiple languages?
- Does it really restart all by itself...or do you need to turn it off first...then restart it by pressing the power button?
- Have you done anything to this computer in the last month...such as installing more ram?

* Nick

pigoo3 said:

Thanks for the info...I'm assuming we are talking about a 20" iMac.

When the computer "restarts itself" does it:

- Show a black screen with a bunch of text in multiple languages?
- Does it really restart all by itself...or do you need to turn it off first...then restart it by pressing the power button?
- Have you done anything to this computer in the last month...such as installing more ram?

* Nick

Click to expand...

Yes, iMac, that's the word I was looking for.
No, text or multiple languages, it just goes black.
Yes, it really restarts by itself. Usually asks me for my password again, sometimes not.
No, I have not added any hardware of software for that matter.

Thanks Nick.

Waterdog said:

Yes, iMac, that's the word I was looking for.
No, text or multiple languages, it just goes black.
Yes, it really restarts by itself. Usually asks me for my password again, sometimes not.
No, I have not added any hardware of software for that matter.

Thanks Nick.

Click to expand...

Ok thanks for all that info.

Before your iMac restarts itself...are the fans running at a high rpm (loud)?

A possibility is we could be looking at an over-heating problem. Your Mac is in the neighborhood of 6-7 years old...and these things do collect dust/fuzz after a while.

I'm not sure if you are up to this...but maybe you can open up your iMac...and give it a good inspection/cleaning. Some of the channels where cooling air is routed may be clogged with dirt/fuzz.

But before you do this...you could download & install a program called "iStat Pro". It's a free program that will provide you with a bunch of computer stats.

In this case we would want to know what your iMac's temperatures and fan rpm's are. This may give us an idea if your iMac is overheating.

- Nick

Thanks Nick. I'm not aware of the fans running loudly. I will start with iStat Pro and get back to you.

Temps:
HD - 97
CPU - 99 to 101
Ambient - 76
CPU Diode - 113
HD Bay - 95
Men Controller - 103
Optical drive - 86

Fans:
Optical Drive - 799rpm
Hard Drive - 1139 rpm
CPU - 809 rpm

I have not idea what ideal temps should be but these sound high. Upon your request I do feel comfortable opening up the iMac and cleaning it out. Is there a video on U-tube?

Those temps and fan speeds look ok. To open up your iMac...go to:

- iFixit: The free repair manual

Look up your iMac model...and follow one of the DIY procedures for opening it up.

Good luck,

- Nick