I'm sure this question has been addressed before, but I can't find it.... so here goes.
In order to keep my system quiet, I'm running most of my case fans at 5v. The fan connectors all use ordinary 4-pin Molex connectors to 12v, so I just switched the pins for the 5v and 12v connections on the first fan in each chain. All downstream fans are connected as normal, with their 12v connector going to the 5v connection from the upstream fan. Just in case it matters, I'm using a 430w Enermax quiet power supply, a 90mm blowhole fan, 80mm rear exhaust, PCI slot cooler (80mm), 2x 80mm front intake, and 2x 40mm hard drive coolers. All of them are LOUD when running at their nominal 12v.
I also tried a few other configurations, such as 6v (2 fans in series from 12v to GND) and 7v (bridged across 12v and 5v connections). The 5v configuration seems to be the simplest AND quietest choice, and its cooling is still sufficient. I've checked the CPU and system temps after running for several hours, and they look fine (51c on my 1800+ after running SETI overnight).
Since I've also got a quiet CPU fan (Silverado with 2 fans at 6v each), the net result is a very quiet system
As far as I know, there are only three problems with this setup:
1) The fans are operating at slightly less than one-quarter power (5/12 squared... unless fan current is constant over voltage?)
2) I could really hose things up if I connect a "normal" component to any of the switched connectors
3) I get funny looks whenever I explain the setup to anyone
Are there any problems that I'm not aware of? Please comment, as I've got four of these configurations running (3 chains of varying length in my system, and 1 chain of 3 fans in my g/f's sytem).
In order to keep my system quiet, I'm running most of my case fans at 5v. The fan connectors all use ordinary 4-pin Molex connectors to 12v, so I just switched the pins for the 5v and 12v connections on the first fan in each chain. All downstream fans are connected as normal, with their 12v connector going to the 5v connection from the upstream fan. Just in case it matters, I'm using a 430w Enermax quiet power supply, a 90mm blowhole fan, 80mm rear exhaust, PCI slot cooler (80mm), 2x 80mm front intake, and 2x 40mm hard drive coolers. All of them are LOUD when running at their nominal 12v.
I also tried a few other configurations, such as 6v (2 fans in series from 12v to GND) and 7v (bridged across 12v and 5v connections). The 5v configuration seems to be the simplest AND quietest choice, and its cooling is still sufficient. I've checked the CPU and system temps after running for several hours, and they look fine (51c on my 1800+ after running SETI overnight).
Since I've also got a quiet CPU fan (Silverado with 2 fans at 6v each), the net result is a very quiet system
As far as I know, there are only three problems with this setup:
1) The fans are operating at slightly less than one-quarter power (5/12 squared... unless fan current is constant over voltage?)
2) I could really hose things up if I connect a "normal" component to any of the switched connectors
3) I get funny looks whenever I explain the setup to anyone
Are there any problems that I'm not aware of? Please comment, as I've got four of these configurations running (3 chains of varying length in my system, and 1 chain of 3 fans in my g/f's sytem).
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