Subject: Optimal CPU temps/Fan configuration
By: East (IP: 68.83.114.*)
Written on: 09-01-2005 09:05

Hi Tillman,

I've found your site immensely helpful. I never used to think twice about how cool my computer was until I started crashing. I was pretty clueless and one of my friends linked me to your site, and many of my questions were answered.

But there is something you or anyone else might be able to shed some light on,
What would you say are optimal CPU temps for an AMD 2500+XP running at standard speed (1836MHz)?

I saw your page of maximum temps and I was curious as to what the best temp range would be.

When my system is idling, the temp hovers around and below 30 degrees C, and under heavy load, I peak in the mid to upper 40's. Is this fairly normal/common. I have 5 fans in my case, four 80's and a 120mm. I guess what I want here is your informed opinion of my fan layout. I'm probably going over the top with this here, so if you don't want to bother, that's fine. Just a simple inquiry...means lots of reading for you haha.

My case is nifty. More or less a beginner's modbox case. I'm not into modding, I just wanted reliable case with a few extras. The Adrenaline Vault did a review of it (, if you're interested in the entire layout of it. It makes it easier for you to have a visual reference of what I'll explain to you. Tell me what you think about my setup.

Starting with the front, there is space for four 80mm's, of which I have put two 80mm's. The front panel of the case detaches but heavily restricts airflow. I have these two front fans pulling air into the case, but the effect is almost negligible. I have the top "blowhole" fan blowing out obviously and the side window fan drawing air from outside directly onto the CPU fan/heatsink. My fifth fan is the 120mm positioned in the back of the case instead of two 80mm's. This 120mm is pulling air into the case. I removed the rear grill so the 120mm could have virtually unrestricted airflow, and it worked amazingly well. Many people have told me that I should flip either the front 2 fans or the 120mm in order to blow out more air from the case. However, if I were to reverse the flow of the 120mm it would draw much of the air from the side window fan directly out of the back of the case. Or if I reversed the front two fans, not much would be blown out, and it would all be cooler air since the fans are at the bottom of the case. The air being blown in now better cools the harddrive than if I were to reverse them, and the 120mm is in a good position to blow air directly over the motherboard. Still I am told that there is too much air blown in and not enough out. What do you think?

Sorry for the enormous post and for being really...really...wordy. I am genuinely interested in what you guys think.

Thanks in advance!


By: Tillmann (IP: 83.121.3.*)
Written on: 09-01-2005 13:32


there is no such thing as "optimal" CPU temperature. For an unoverclocked CPU, any temperature below 85C (the maximum temperature for your CPU) is fine.

Since your CPU temperatures are way below that, and you are not overclocking, I suggest reducing the amount of fans, and/or fan speed (see tips in the "Connectors" section, or the "Temperature control" section), to lower the noise of the system.

Concerning fan orientation: To get proper air flow, fans should blow in the same direction, even when installed on opposite sides of the case. So, if your case front fans are blowing in, your back fans should suck out. In any case (even if you disable the front fans), it is better to have the 120mm back fan exhaust air. Otherwise it may create a "short circuit" in air flow together with the power supply fan (which exhausts), as you can see in the illustration in the case cooling section here on the site.

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