06-16-2009, 11:03 PM

need any info / help. My Mac Pro 2.66 will restart, restart , restart and restart sometimes till half an hours before you see the logon page ! Especially when its cold. Everyday when I come home, press the power buttom , there is a " click " sound ( can see the Red light on/off from the back of the machine ). then the unit will restart itselfs. restarts x 10 times / 20 times !
But when it finally come to OS X or Window XP ( I run both with boot camp in between ) everything is normal without turning off !!!!
p.s. checked with Ram ....installed new ram.......same thing happened !
checked hard-drive .......got new hard drive.......same thing happened !
Bought to " Total Mac " store repair Mac machine, nothing's wrong , one time only to start up ......**** !!!!!! Guys any idea ???? would it be the power unit ? but if its the one, how to explain when the machine is hot, can restart without problem !!! THX in advance for any idea !!!!!

06-18-2009, 04:18 AM

I recommend that you make sure your Fans are working correctly.

smcFanControl is a pretty good software(if you can get your mac to boot)
iStat widget is good for fans+temperature.

but tbh i think its caused by corrupt software.

I also noticed that if i have a mass storage device attached while im starting up the computer, the boot time increases by 10~20 seconds.

06-18-2009, 08:44 PM

THX Hildezard,
but the fan is working once the machine is power on, and I've changed another new hard drive + all my data stuffs is in other drive not the OS drive !!!

06-19-2009, 04:31 AM

Originally Posted by Jeff3231

THX Hildezard,
but the fan is working once the machine is power on, and I've changed another new hard drive + all my data stuffs is in other drive not the OS drive !!!

Yes the fan might work. What you need to check whether the fans working correctly or incorrectly. This happened to me on a pc and i hear some video cards(my very own 1900XTX and some 8800 i think) also have this on macs.

The fans work as the ear can tell but they fail to cool the gpu hence they flail around. Since you said that it fails to work when its cold im guessing that the temperature your cards/or motherboard or ram or wtw get are correct at first but the fans work at low.

Working at low at the startup and when the temps get high(e.g. you booting up) they need to work at a steady pace to constantly cool it. if they fail to work steadily correctly then your symptoms make sense to me.

Of course there are far more advanced users here who know better than me. Thats just my assumption.

06-21-2009, 06:54 PM

What temperature is the room at when you try to fire the Mac up? I ask because my 30" ACD had a similar problem when the room was pretty cold from a window being open, after 30 mins it would stay on no problem.

Have you tried resetting the PRAM (holding down cmd+opt+p+r as you switch it on until you hear a second chime)?

Have you tried running the Apple diagnostic test found on the DVD that came with your Mac?

Aside from that I could only guess it is a power supply / logic board issue.

If it is a hardware issue something has gotten too hot and has come loose from the connection/solder joint and only when the temp rises is it regaining a connection and the Pro appears to be fine.

06-21-2009, 08:31 PM

many thanks Hidezard & martyp for those info. Today my MacPro needed exactly 1 hr and 15 min to start up to reach the Windwo XP page.....!!!!! For the first 10 - 15 mins, once I press the power button, The " click " sound & the machine restart right a way : mean click , restart , click - restart, click - restart , then after half an hour: click........restart, getting longer time between click and restart .....finally reachese the main window page !!! I call the guy from craigslist.....Mobilemactechs, they said the logic board more than likely has been tripped(needs resetting). Since I've send the unit to a store name " Total Mac " and they couldn't find anything ( the machine was normal there ) I have no choice and give them a try tomorrow ........!!!!! again thanks guys for those advise !!!!!

07-12-2009, 07:26 AM

no problem. Why dont you just install win 7 Rc???then buy a 64bit of it when it comes out?

or to the 10-step flash disk windows startup thing.

or get a new maC

12-14-2009, 10:33 AM

Hi there, I'm having the exact same problem you are. When I boot the computer cold, it starts, dies, starts, dies. Then I've to press the power button again and the same thing happens until eventually it boots. If it had been on for a while on a shut it down and reboot it starts first time.

I'm wondering if you've found any solution to this problem? Was it the power supply or the logic board or anything else. Any info would be great! Thanks alot : )

12-14-2010, 05:58 AM

My apologies if this topic has already been solved here or on any other Mac forums.

I've been following the forums regarding problems when cold starting a Mac Pro. I've had this problem on and off for over 12 months now, and in spite of using some of the suggested solutions, I've had little success in solving it. Now I'm not an IT expert but it occurred to me that if the problem only occurred when cold starting [i.e. starting up in a cold environment] then the solution might be something to do with the temperature inside and outside the Mac Pro? I couldn't find a simple solution on any of the Mac forums [including Apple's vast support] so I tried a few experiments anyway. One solution which was suggested on the Mac forums, was to 'sleep' the machine rather than powering down. This was a limited success but it sometimes still shut down and restarted several times, especially when the temperature got below about 5 degrees.

Now my Mac is located in an unheated room [actually a shed or den if your in the US] and it gets pretty cold out there during the late autumn and winter which is when the problem mostly occurs. One solution would have been to keep the room heated, which seemed a bit like overkill for the amount of daytime I actually spent in there.

I then bought a 2 foot tubular [sometimes called greenhouse] heater for about £30. They are cheaper from Ebay but I was in a hurry by now. I placed it at the side of my Mac hoping that this would be the ultimate solution. Once again it was a limited success but still didn't deliver the instant start up every time [with or without 'sleep' mode in operation].

I realised that little of the heat [the heater is rated at 120 watts] was actually affecting the Macs temperature. I then decided to build a box with inlet and outlet holes, to contain the heater and put it underneath the Mac. I of course, first checked the heater was suitable for being contained in a box and sure enough, they are apparently often enclosed like this anyway. There are minimum clearance dimensions supplied with the heater to ensure that it doesn't overheat. It also has a thermal trip, just in case.

With the Mac installed on top of the box I rebooted, put the computer to 'sleep' and left it overnight. It just happened that on that particular night we experienced a temperature of minus 8 degrees which is pretty cold for the English midlands. The actual room temperature in my shed was minus 4, so after checking that the bottom of the Mac was nicely warm, I apprehensively clicked the mouse and waited for the inevitable crash. Well it didn't and much to even my surprise, it didn't have to restart several times the following very cold morning when I restarted the machine from scratch. It's almost four weeks now since I first installed my hi-tech Mac Blanket and it hasn't performed an unexpected restart since.

I realise that there may be some warnings forthcoming about overheating etc., but the bottom of the Mac is only just warm so I'm happy to continue with the experiment until the spring.

Hope this helps if anyone is still struggling with a cold starting Mac.

12-14-2010, 08:48 AM

^Wow. Great post/info.

12-14-2010, 01:39 PM

An easier solution: Keep your Mac in a heated room during the Winter. I can't imagine doing any kind of work on my machine sitting in a cold room that's approaching freezing temperatures. Keeping me warm is an even greater priority than keeping my Mac warm.

12-14-2010, 02:10 PM

Originally Posted by chscag

An easier solution: Keep your Mac in a heated room during the Winter. I can't imagine doing any kind of work on my machine sitting in a cold room that's approaching freezing temperatures. Keeping me warm is an even greater priority than keeping my Mac warm.

Yes...when I read this thread earlier I was thinking the same thing...as well as the recommended operating temp. specs from Apple (click on "tech specs" in the link):

Mac Pro - Buy Mac Pro desktop computers - Apple Store (U.S.)

...Apple recommends 50°F - 95°F.

@OP: What's probably mostly effected by the colder temps is the lubricant used in the bearings of a hard drive. Just like lubricants in a automobile (or anywhere else lubricants are used)...cooler/colder temps make the lubricant more viscous...which then requires more effort to get the hard drive spinning.

- Nick

12-14-2010, 04:02 PM

Perhaps a solid state drive may well be the go?

12-14-2010, 04:05 PM

Originally Posted by harryb2448

Perhaps a solid state drive may well be the go?

Now there's a good idea (as long as cost isn't an issue)...an SSD certainly would be less effected by colder temps than a traditional "spinning" HD.

- Nick