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drive-bay fan control = bypassed motherboard fan headers?

Posted: Fri Oct 16, 2009 12:59 pm
by nothingworks
I'm half-embarrassed to ask this because it just "feels" like a really ignorant, smack-worthy question, but I can't find the info I'm looking for, so here goes nothing.

If you install a drive-bay fan controller such as the Scythe Kaze Master Ace / KM02, you can independently control four fans. If you have this connected to your CPU fan and a few case fans, does this mean these fans won't be connected to the fan headers on your motherboard?

I assume the short answer is yes, and the long answer is there is no reason to connect them to the mobo (for fan speed control through BIOS or software) if you're manually controlling them from a drive bay.

If I have this right, would I lose any other functionality by not connecting fans directly to the motherboard?

Not sure if you can tell, but I've never built a quiet PC before. :wink:

Posted: Fri Oct 16, 2009 6:13 pm
by khaakon
The short answer is right, and the long answer is right too but i would perhaps change the word 'reason' with 'possibility' - because you can't have two controllers controlling one fan (unfortunately :o ).

When you decide to manually control your fans, you will ofc lose automatic fan control which revs up fans as temp go up, for better cooling. This might be critical especially for the CPU fan. Unless you also plan to install temp sensors aswell, then your fan controller might do the job that motherboard/bios normaally does.

Posted: Fri Oct 16, 2009 7:12 pm
by bonestonne
don't forget to disable the BIOS setting that warns you about fan failure...not plugging the fan into the motherboard header will make it think the fan is dead, and your PC will just shut off. wont be overheating at all, but it wont let you start.

i don't know if all motherboards have this, but it will save a great deal of trouble if you know to check this first.

Posted: Mon Oct 19, 2009 8:57 am
by nothingworks
Thank you, both, for the answers and advice.

My main issue was that I'm shopping for a motherborad that's compatible with the i5 / LGA 1156 socket, and is mATX form factor. From what little choice that's currently out there, there are fewer fan headers on the mobos than the larger ATX counterparts. I figure getting an external controller such as the Scythe Kaze Master Ace KM02, would help control more fans. (Even 4 vs. 3 is helpful.)

Granted, I suppose having to manually monitor and adjust isn't as convenient as having BIOS settings do it, but I am thinking I won't be micromanaging as much as just working with two fan settings: when gaming, I'll just crank them up, since I'll have the headphones on anyway.

Posted: Mon Oct 19, 2009 12:26 pm
by reddyuday
Hi, I was planning to go in the same direction by mounting a fan controller, but found that I didn't need to.

I am running my system with a single 120mm CPU fan mounted on Akasa Evo. (My motherboard has two fan headers.) The CPU fan is directed towards the back of the case and, so, serves as an exhaust fan as well. E6750 runs at around 43C normally. The motherboard temperature is generally below 40C.

I have another exhaust fan behind the CPU cooler, which I turn on if the CPU gets a bit hotter, but I found that turning it on doesn't make that much of a difference, maybe just 1-2C.

So, depending on the air flow in your case, you might not need very many fans. You might try it out with fewer fans and see how it works. I have a feeling that the fin area of the cooler matters a lot more than the fan blast.

Posted: Sat Nov 07, 2009 2:56 am
by reddyuday
reddyuday wrote: I am running my system with a single 120mm CPU fan mounted on Akasa Evo. (My motherboard has two fan headers.) The CPU fan is directed towards the back of the case and, so, serves as an exhaust fan as well. E6750 runs at around 43C normally. The motherboard temperature is generally below 40C.
A significant correction. The E6750 is running at 34C, not 43C.

I have had the motherboard software and Speedfan report different temperatures for the CPU, the motherboard software reporting much higher temps than Speedfan. After thinking about it and checking various things, I have come to the conclusion that the Speedfan temps are right. They are either the same or a couple of degrees above the temps that the CPU itself reports for its cores. The "motherboard temperature" is generally below 40C, as I mentioned earlier. The motherboard software and Speedfan agree on this. The hard drive is also between 30-35C.

This result quite amazes me. A single 120mm fan, running at only 600rpm, mounted on a skinny CPU cooler, is enough to cool a system built on Core 2 Duo at 2.66GHz! So, why do people need lots of fans?

Posted: Sat Nov 07, 2009 1:12 pm
by danimal
case fans are not so much for the cpu cooler, as you've found, but they are really nice for a high-performance video card that's making the case air hot, and/or for pulling in cool air across a hard drive.