How come my Sharkoon 2000rpm fan only hits 1880rpm?

And then settles at around 1865 to 1869rpm. This is with smart fan disabled in easytune. Would it go to 2000rpm if I disabled cool n quiet in bios? I read that fans rated at a certain speed usually go a bit over the rated speed, let alone under it.

Why don't you plug them directly to the power supply?

Nebulous said:

Why don't you plug them directly to the power supply?

Click to expand...

Well I could try that, but is this a case of fan specs being misleading and perhaps the sharkoon is actually rated at 1800rpm? Shouldn't the cpu fan header (which this sharkoon is using) do the same job as a molex to psu?

I dunno, fans are mass manufacturered, and the ones we buy lots of times aren't uber top notch. Top meaning a $1300 480V 3 phase fan pulling 7 amps, 14" diameter or so. It WILL cut a finger off no problem, on the back of our 128 main drive motors. Grr can't remember the brand, but I see the manu spec shhet from the catalog in my head.

So I can see a 15% variability in lots of the fans we buy, and another 5% in the mobo. They aren't industrial quality by any means. Deltas, yes, they have a name to defend. Fan RPM isn't the main thing that matters when making a mobo.

So yea, it's a big diff but nothing that suprises me much.

Measure the mobo 12vdc for the fan header when it's at max speed, good chance it's not 12V.

Is the fan on your cpu heatsink? The load from pushing air through the heatsink will slow it down. Try it in open air and see what it does.

^That's what I was thinking. Almost anything it's mounted to will cause negative (or positive while pushing) pressure to build between it and the blades, slowing them down some.

There is also the fact that a fans rated RPM's are almost always rated +/- 10%. If the fan is rated at 2000 RPM, that leaves 200 RPM of leway, giving you anywhere in the range of 1800-2200 RPM's that your fan will spin at under normal operating conditions.

Thanks for the replies guys, sorry I didn't reply sooner, totally forgot I'd posted this, lol! Yeah, I suppose you're right, there could be a 200rpm leeway +/- .

Bobnova, yeah, it's on the cpu header, attached to the TRUE. I disabled cool n quiet to see if it would change anything but it doesn't. I'll do some of that open air testing. I'm collecting two more AC Ryan 77.70cfm 2000rpm fans from the post office first thing tomorrow morning (went there today to collect but was closed due to stupid industrial action, grrrr ) and am replacing the side fan and the front fan with them. I use the sys fan header for the side fan and can monitor the speed in HW Monitor.