Tie case fans to cpu temp?

Armadillo · 8 Mar 2017 at 23:58

Wasn't sure if this should be here or in motherboard section as it's a bit of both I guess.

Anyway. Looking to overclock my 5820K. Testing at 4Ghz @1.15V and under stress testing maximum temp is 77C with my K2 spinning fans at max. Not bad, but sure the cooler is capable of better.

Quick check and the case fans were still almost at idle speeds. Testing with the case fans manually set to max (1200rpm) and then stress testing and it's 62C max, 15C difference.

Looking in the bios and there does not seem to be a way to make the case fans change speed based on cpu temp. It seems they are tied to the temp sensors on the motherboard. On this board (GA-X99-SLI), according to the manual, the sensors are located near the bottom of. The board is in a big case (Corsair 750D), near enough in direct path of the lower fan, so they don't really move much. Between idle and load there's probably 5C difference, which results in the case fans going from about 700rpm to 750-800ish.

So wondering if there is a way round it, as it's seriously hurting temps. Software? or is what the bios says final?

Thanks.

bremen1874 · 9 Mar 2017 at 00:13

Connect one or more of the case fans to the CPU_OPT connector?

Armadillo · 9 Mar 2017 at 02:07

Always thought that was for watercooling pump. After actually checking manual does actually say it's for a watercooling fan, so that'll work. I want all 3 to go with the cpu temp. So I guess I'll be needing a hub/splitter that has it's own power, as I have no idea what the fans draw or what the header can give.

This will do the job I think

https://www.overclockers.co.uk/akasa-flexa-fp3s-3-fan-pwm-controller-ak-cbfa06-30-cb-000-fs.html

?

Grab that, 3 case fans into it, set disered fan curve for cpu_opt in bios and fans will move with cpu temp.

Thanks.

bremen1874 · 9 Mar 2017 at 02:17

I'd have fair confidence that a single header would support three standard case fans. As usual the absence of real numbers makes it a guessing game.

Are the case fans PWM? If not I don't think that adapter will help you.

Armadillo · 9 Mar 2017 at 03:21

bremen1874 said:
I'd have fair confidence that a single header would support three standard case fans. As usual the absence of real numbers makes it a guessing game.

Are the case fans PWM? If not I don't think that adapter will help you.

Case is a Corsair 750D. All three of the stock 140mm fans are pwm.

Atari · 9 Mar 2017 at 10:08

I bought a Phobya PWM 8-fan hub for a few quid after a recommendation from Doyll on the forum. Simple to set up and just works.

I've also set the lot to run off a Speedfan profile which keeps the system dead silent at idle, and ramping up incrementally when needed.

Armadillo · 11 Mar 2017 at 04:34

I saw that, powered by molex for some reason. I don't know why so much stuff is still powered by molex rather than sata for power. I know it can run unpowered, but I'd rather err on the side of caution. My fans are all pwm, so looking at the reviews, it seems the akasa cable should work for now. Unless anyone can see why it wouldn't for what I want, I'll order one over the weekend.

I really think by now what header reacts to what temp should be customisable in bios. It seems silly to have the case fans react to only ambient case temp, which in a large case doesn't fluctuate much at all. Unless they just expect everyone to be using an aio rather than air cooling now.

doyll · 11 Mar 2017 at 13:46

Armadillo said:
I saw that, powered by molex for some reason. I don't know why so much stuff is still powered by molex rather than sata for power. I know it can run unpowered, but I'd rather err on the side of caution. My fans are all pwm, so looking at the reviews, it seems the akasa cable should work for now. Unless anyone can see why it wouldn't for what I want, I'll order one over the weekend.

I really think by now what header reacts to what temp should be customisable in bios. It seems silly to have the case fans react to only ambient case temp, which in a large case doesn't fluctuate much at all. Unless they just expect everyone to be using an aio rather than air cooling now.

PWM fans use constant 12 volt power on pin-2. This 12v power is pulsed by the PWM circuit in the fan using the PWM signal received on pin-4.
End result is we can control the fan speed of like 8-10 fans using a single motherboard PWM fan header without any chance of damaging it because all the power is supplied directly from PSU.