Blowing air at the motherboard with a fan inside the case
Posted: Sat May 03, 2014 9:13 am
I have a first generation Antec Sonata case. I chose it for quietness, but never tried to modify it to make it really quiet. Noise sources inside were the 120 mm rear fan, the stock CPU cooler, the PSU fan, and the hard drive. Most noise is from airflow, and the rear fan, which is probably getting a bit louder from age now.
I just did an experiment, adding a 120 mm fan inside the case blowing at the motherboard. It's mounted on two angle brackets connected to two 120 mm fan mounting holes on the hard drive cage, with rubber grommets for vibration isolation. (Normally, the fan there is meant to be mounted on 4 holes for blowing air front-to-back.) I'm running it at only 5 volts, and it's almost silent. It's making a big difference in northbridge heat sink and memory heat spreader temperatures. The northbridge heat sink used to be so hot it was painful to keep my finger on it, and now it's just a bit warm. The sensor differences are less impressive, but temps are down a few celsius.
The theory behind this is that all the empty space in the case provides a low resistance path for airflow, and all the stuff sticking out from the motherboard slows airflow there. The added fan makes air flow by the motherboard, cooling it better. Bringing in air from the outside should provide better cooling, but it would also require cutting a hole in the case and probably result in more noise
I wonder what others think of this idea?
It seems I could change the exhaust fan from medium to low speed now, which greatly quiets the case, leaving the CPU fan as the most prominent noise source when it speeds up. I'm still a bit afraid to leave it that way though, wondering if some hot spots might form. I'm also wondering whether to replace it with a low noise version and/or modify the case to improve air intake.
I just did an experiment, adding a 120 mm fan inside the case blowing at the motherboard. It's mounted on two angle brackets connected to two 120 mm fan mounting holes on the hard drive cage, with rubber grommets for vibration isolation. (Normally, the fan there is meant to be mounted on 4 holes for blowing air front-to-back.) I'm running it at only 5 volts, and it's almost silent. It's making a big difference in northbridge heat sink and memory heat spreader temperatures. The northbridge heat sink used to be so hot it was painful to keep my finger on it, and now it's just a bit warm. The sensor differences are less impressive, but temps are down a few celsius.
The theory behind this is that all the empty space in the case provides a low resistance path for airflow, and all the stuff sticking out from the motherboard slows airflow there. The added fan makes air flow by the motherboard, cooling it better. Bringing in air from the outside should provide better cooling, but it would also require cutting a hole in the case and probably result in more noise
I wonder what others think of this idea?
It seems I could change the exhaust fan from medium to low speed now, which greatly quiets the case, leaving the CPU fan as the most prominent noise source when it speeds up. I'm still a bit afraid to leave it that way though, wondering if some hot spots might form. I'm also wondering whether to replace it with a low noise version and/or modify the case to improve air intake.