Tempermental fan in new build

It sounds like something is obstructing the motor maybe, maybe a dustbunny or something. Or I suppose it could be some bad bearings? Anyway, if you have some canned air I would at least try that, if not, just buy a new fan and hook it up the same way the bad one is.

Cheers for the reply. About ten minutes ago I tried swapping around where the fans were connected to the motherboard and lo and behold, the one that was working fine doesn't start, and the temperamental one now starts straight away, albeit not as high RPM as the other fan when its working properly. Does this indicate a problem with the motherboard?

does your mobo have a lot of fan controls?

It may not be giving enough voltage to that particular fan. Usually fans need a minimum voltage to get started, and then can keep spinning if voltage is reduced down a bit, which is why it works with your nudge-start.

Could be the settings for that particular fan control are lower so a fan settings issue, or a mobo issue.

But as you remarked the fan spins slower, so that particular fan might be a bit less smooth too.

If it doesn't bother you, maybe just let it go for now.

Thanks for the suggestions, I'll have a root around later. I know what you mean about just leaving it, it's spinning at about half the speed of my other intake fan, and I've also got an exhaust fan, should I be alright in terms of cooling when playing games (specs - windforce 7870, 8GB vengeance, 128GB SSD, 3570k with stock cooler)?

Good point. I wonder if maybe the 12V pin on the molex isn't making contact?