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Maximus Gene V - Low CPU Fan RPM

Level 7
Hey all-

First time poster, first time ROG board owner, third asus board build

So I am having this issue (at least I think its an issue) with my CPU Fan RPM. Its RPM is very low all the time and I can't seem to figure out why this is the case. My current fan setup is I have 3 Noctua NF-P12's in my case. 2 are connected to the chassis headers as PWM and the 3rd is used as the CPU fan for the radiator and is hooked up to the CPU_FAN header as PWM. The pump for the H80i is hooked up to the CPU_OPT with its 3-pin connector. At first I didn't think this was an issue as maybe the low ambient temperature just wasn't making the RPM's rise, but as a test I started up BF3 and played for about 15 min and watched the RPM's of the fans and none of them changed. I would really think that the CPU Fan on the radiator would regulate itself based on load and change its RPM on the fly. Am I correct in thinking this? Please let me know if I am missing something and yes I am a noob when it comes to ROG boards and the AI suite stuff.

If possible my preferred solution would one where I do not have to use AI suite to make it work but rather the Bios would or mobo would regulate the CPU fan, but if not oh well.

Oh yea, forgot to mention that I had to set my CPU low level to 200 in the Bios just to get by the Cpu Fan error post boot

Thanks all for any help


Silverstone FT-03
Asus MAximus Gene V
3507K stock speed
Corsair H80i cooler
Samsung 128 GB 840 Pro Series SSD
Radeon HD 6970
Corsair 8GB Dominator Platinum @ 1600C8
All Fans - Noctua NF-P12

Level 15
Welcome to the Republic of Gamers forums, smitty8100.

From looking at your settings, you programmed it to only ramp up to 100% when the CPU hits 70C. So unless you hit 70C while playing BF3, the fan won't change its speed. The fan regulates itself using temperature as a guideline, not the amount of load you're putting on the CPU.

Chino -

Thanks much for the response. Had no idea that it was based off the temp and not cpu load. So I basically just need to re-arrange my setting so that the RPM will kick up earlier as the temp goes up. One last thing, is common for this board or other ROG boards to have to set your CPU Low Limit so low just to get past boot? Is that because of the PWM?

Also, can someone confirm for me that the best solution for the H80i pump is to have that in the CPU_OPT header?

Thanks all and look forward to utilizing this forum in the furture

Level 15
Not sure about other Asus boards, but the ROG line has the built in fan protection mechanism. So by default, your fans should be spinning at a certain speed to not set off the sensor. That's probably why you got an error earlier. Maybe yours was spinning slower than the default speed.

Personally I think it's a good feature to have because it'll let you know if the heatsink fan is dying and spinning slower than normal or if the fan suddenly died or something. If this both bothers you, you disable it in the BIOS. But I'd advise you to not do that. lol

The CPU_OPT header is there in case some modern heatsinks have a crazy amount of fans connected to it and you need another header to connect them. It functions just like the normal CPU_FAN header. I don't see any problems with you connecting the pump to it. From your screens, it's running at 2266RPM which sounds just right.

Level 7
One last thing, is common for this board or other ROG boards to have to set your CPU Low Limit so low just to get past boot? Is that because of the PWM?

i just want to know this where do you get this idea that you have to set CPU Low Limit to get fast boot ?
i7 3770k @ 4.0 | Corsair H60 | Maximus V Gene | 4gb x 4 Crucial Ballistix Elite | Asus GTX 660ti TOP | Corsair Force GT 120gb | WD Caviar Black 1TB | Seasonic x-660 | Fractal Design Define Mini |