Overheating Problems

2010-12-12, 02:38

I have a 4 month old Macbook Pro and run GIMPS. I found that even if I elevate my computer in such a way that both the CPU and fans are exposed to open air, CPU temperature never droppes below 85C, and peaks at 92C. Is there anything I can do to lower this? I want to run GIMPS overnight but I am not comfortable with leaving something that hot on all night. Is there a setting or something to lower CPU usage?

mdettweiler · 2010-12-12, 05:27

You may want to try adding the following line to prime.txt in your Prime95 directory:
Throttle=n
where n is the percentage of time that Prime95 should run. If, for instance, this is set to 50, Prime95 will run for one second, pause for one second, etc...(I'm not sure of the exact time intervals but it's something on that order of magnitude). You can play around with various values of n to see what is optimal to keep your laptop in a more desirable temperature range without sacrificing too much performance.

Additionally, there are a few other tricks which you may or may not have tried already to reduce your laptop's heat; using these in concert with the Throttle option may allow you to reduce the throttle threshold (perhaps entirely). Namely:

-Keep the lid open.
-Put the laptop on something that will allow to circulate under it. A standard kitchen cooling rack works well for this (though it can be a little funny to type on since it's kind of springy--at least mine is

).
-Stick an ice pack under the laptop. Okay, it's a little drastic (not to mention high-maintenance, since you'd have to re-freeze it for each night), and it is mutually exclusive to the cooling-rack strategy (since the laptop has to be in physical contact with the ice pack for maximum efficacy), but in my experience it works quite well to cool down the laptop VERY quickly. Flexible ice packs that can be laid flat are ideal, though solid Blue Ice containers can work in a pinch. Just make sure to put a cloth between the ice pack and the laptop to keep condensation from wetting the laptop too much.

Again, you may have already tried some or all of these, but if you haven't they might help some. Other people may also have suggestions that I haven't thought of here.

Hope this helps!

Ken_g6 · 2010-12-12, 08:18

If you're feeling a bit more adventurous, you could try some manual underclocking/undervolting.

vsuite · 2010-12-13, 00:54

I would advise getting a desktop for prime95, and you can leave the monitor off most of the time. But if you are using a laptop,

1. Please never leave the machine running prime95 with the lid closed. You will eventually damage the screen I'm certain. So, the machine settings must be to standby or hibernate once the lid is closed.
2. Never use the laptop on a soft surface like a bed or sofa. The vents will get blocked.
3. Get a laptop cooler fan (that plugs into the USB) and leave it running. It will prop up the laptop and send cool air to the vents.

4. Use the throttle= setting ... or ...
5. On Vista or Windows 7, Right-click on the Desktop, choose Personalize, Screen Saver, Change Power Settings, [Preferred Plan]Max Battery, Change Plan Settings, Change Advanced Power Settings: you can set the min & max Processor state to 5% and 50%, or even lower. Of course you will perform proportionally less GIMPS. Note that if you run mfaktc, the GPU will run at full speed, so lowering the max CPU state will not proportionally lower the processing power. For me max CPU of 50% doubled prime95 factoring time, but increased mfaktc time by about 11% iirc. I'm really not sure the comparable setting on OSX.

Uncwilly · 2010-12-13, 06:33

Quote:

Originally Posted by vsuite

But if you are using a laptop,

I have found that running TF's only on my laptop keeps the fan at a much lower speed than P-1's or LL's. HTH

2010-12-12, 02:38	#1
160274 2×23×79 Posts	Overheating Problems I have a 4 month old Macbook Pro and run GIMPS. I found that even if I elevate my computer in such a way that both the CPU and fans are exposed to open air, CPU temperature never droppes below 85C, and peaks at 92C. Is there anything I can do to lower this? I want to run GIMPS overnight but I am not comfortable with leaving something that hot on all night. Is there a setting or something to lower CPU usage?

2010-12-12, 05:27	#2
mdettweiler A Sunny Moo Aug 2007 USA 14232₈ Posts	You may want to try adding the following line to prime.txt in your Prime95 directory: Throttle=n where n is the percentage of time that Prime95 should run. If, for instance, this is set to 50, Prime95 will run for one second, pause for one second, etc...(I'm not sure of the exact time intervals but it's something on that order of magnitude). You can play around with various values of n to see what is optimal to keep your laptop in a more desirable temperature range without sacrificing too much performance. Additionally, there are a few other tricks which you may or may not have tried already to reduce your laptop's heat; using these in concert with the Throttle option may allow you to reduce the throttle threshold (perhaps entirely). Namely: -Keep the lid open. -Put the laptop on something that will allow to circulate under it. A standard kitchen cooling rack works well for this (though it can be a little funny to type on since it's kind of springy--at least mine is ). -Stick an ice pack under the laptop. Okay, it's a little drastic (not to mention high-maintenance, since you'd have to re-freeze it for each night), and it is mutually exclusive to the cooling-rack strategy (since the laptop has to be in physical contact with the ice pack for maximum efficacy), but in my experience it works quite well to cool down the laptop VERY quickly. Flexible ice packs that can be laid flat are ideal, though solid Blue Ice containers can work in a pinch. Just make sure to put a cloth between the ice pack and the laptop to keep condensation from wetting the laptop too much. Again, you may have already tried some or all of these, but if you haven't they might help some. Other people may also have suggestions that I haven't thought of here. Hope this helps! Last fiddled with by mdettweiler on 2010-12-12 at 05:28

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2010-12-12, 08:18	#3
Ken_g6 Jan 2005 Caught in a sieve 395₁₀ Posts	If you're feeling a bit more adventurous, you could try some manual underclocking/undervolting.

2010-12-13, 00:54	#4
vsuite Jan 2010 72₁₆ Posts	I would advise getting a desktop for prime95, and you can leave the monitor off most of the time. But if you are using a laptop, 1. Please never leave the machine running prime95 with the lid closed. You will eventually damage the screen I'm certain. So, the machine settings must be to standby or hibernate once the lid is closed. 2. Never use the laptop on a soft surface like a bed or sofa. The vents will get blocked. 3. Get a laptop cooler fan (that plugs into the USB) and leave it running. It will prop up the laptop and send cool air to the vents. 4. Use the throttle= setting ... or ... 5. On Vista or Windows 7, Right-click on the Desktop, choose Personalize, Screen Saver, Change Power Settings, [Preferred Plan]Max Battery, Change Plan Settings, Change Advanced Power Settings: you can set the min & max Processor state to 5% and 50%, or even lower. Of course you will perform proportionally less GIMPS. Note that if you run mfaktc, the GPU will run at full speed, so lowering the max CPU state will not proportionally lower the processing power. For me max CPU of 50% doubled prime95 factoring time, but increased mfaktc time by about 11% iirc. I'm really not sure the comparable setting on OSX.