Posted by: reformedmusings | July 23, 2011

A tale of 3 case fans in one computer – important safety tip

I wrote earlier about Unity in Ubuntu Natty 11.04 and its lack of ability to monitor system parameters such as CPU and GPU temperatures in a simple panel applet. I always display and monitor these two parameters in Avant Window Navigator dock. This week provided a case in point as to why I find this important in my overclocked Ubuntu system.

I noticed that one of my three case fans, the most visible one with the blue LEDs in it, had quit. It had been vibrating for a while but I was too busy to mess with it. The fan eventually quit making noise, so I assume it quit even though the LEDs continued to work. About that time, I noticed that my CPU Core #3 temperature rose to about 52C at idle and close to 60C under load. It previously hovered in the low 40’s. Worse, my GPU temperature went from the mid-50’s to close to 80C! So, I ran over to our local Micro Center to pick up an Antec 80mm case fan w/blue LED to replace the seized one.

After replacing the fan, I turned the computer back on with the side panel opened to make sure that I didn’t knock any connections loose. When the computer started running, I noticed that the primary case fan at the back of the case and the one over my video card weren’t running. Apparently, all three case fans had failed at some point! No wonder the CPU and GPU temperatures rose so much.

I picked up an 80mm Silenx Ixtrema fan for the primary fan position in the back of the case. It advertised 14dBa for quiet operation and has fluid dynamic bearings for long life. It also came with silicone mounts for vibration isolation, but that would be overkill with the huge Zalman CPU fan and the 30 dBa blue Antec case fan running. Seemed a good choice. For the lower side fan, I chose an 80mm T.B. Silence from Enermax, which matched the black color of the panel on which it is mounted and it was rated at only 15 dBa.

As I installed these in the case, I noticed that all three of the new fans had the proper 3-pin connectors to attach to the Gigabyte EP-45 motherboard. I used those motherboard connections rather than running the fans directly off of the power supply (as I had done with the old ones) so that their RPMs could be monitored through the AWN sensor applet. I also set alarms on them for low RPM so that I will be warned of failures. Now all the fans in the case except for the power supply fan are monitored through the excellent lm-sensors and the AWN sensor applet.

While I was in the case, I swapped the leads around on the hard drive activity LED. The Smilodon case instructions provided the proper installation for the red/white lead wires to the motherboard. The only problem is that there aren’t any red/white wire pairs in the case. I tried to guess at the correct setting with the lead labeled HDD, but guessed wrong when I upgraded the hard drives a while back. After swapping the connector around, the HDD-access LED works again.

Net result today is that the CPU Core #3 (always the warmest of the 4 cores) dropped 10 degrees C back to 42 at idle and now has yet to top 44 under load. The GPU core dropped over 20C from 76-77 at idle to 56C. Once again, the Smilodon case was a dream to work with, with both sides opening up for easy access to everything inside.

So, here’s the important safety tip – check your case fans periodically, and keep an eye on your CPU and GPU temperatures. It would be a real bummer to fry $200+ silicon because of a $10 fan failure.

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