[SOLVED] Tapping Noise from Noctua AF14

[barnyard80]

I have 4 Noctua A14 fans in my Meshify C case.

2 are front intakes.
The roof/front fan is intake
The roof/rear is exhaust.

All A14 fans are connected to a single fan header via Noctua Y splitters.

They are set to low RPMs.

Sometimes, the front/lower fan makes a tapping noise for a few seconds/minutes. But then it goes away. What could cause this?

https://uk.pcpartpicker.com/list/LrQj3t

PCPartPicker Part List

CPU: AMD Ryzen 9 3950X 3.5 GHz 16-Core Processor (£650.00 @ Amazon UK)
CPU Cooler: Noctua NH-U14S 82.52 CFM CPU Cooler (£65.47 @ Scan.co.uk)
Motherboard: Asus TUF GAMING B550-PLUS ATX AM4 Motherboard (£145.99 @ AWD-IT)
Memory: Corsair Vengeance LPX 32 GB (2 x 16 GB) DDR4-3200 CL16 Memory (£123.48 @ Ebuyer)
Storage: Samsung 970 Evo Plus 1 TB M.2-2280 NVME Solid State Drive (£171.00 @ Amazon UK)
Storage: Seagate BarraCuda 1 TB 3.5" 7200RPM Internal Hard Drive (£36.48 @ Aria PC)
Video Card: MSI GeForce GT 1030 2 GB 2GH LP OC Video Card (£66.09 @ CCL Computers)
Case: Fractal Design Meshify C ATX Mid Tower Case (£101.03 @ Overclockers.co.uk)
Power Supply: Corsair RMx (2018) 750 W 80+ Gold Certified Fully Modular ATX Power Supply (£114.99 @ AWD-IT)
Case Fan: Noctua NF-A14 PWM 82.5 CFM 140 mm Fan (£21.94 @ CCL Computers)
Case Fan: Noctua NF-A14 PWM 82.5 CFM 140 mm Fan (£21.94 @ CCL Computers)
Case Fan: Noctua NF-A14 PWM 82.5 CFM 140 mm Fan (£21.94 @ CCL Computers)
Case Fan: Noctua NF-A14 PWM 82.5 CFM 140 mm Fan (£21.94 @ CCL Computers)
Case Fan: Noctua NF-A15 HS-PWM chromax.black.swap 82.52 CFM 140 mm Fan (£28.68 @ Overclockers.co.uk)
Total: £1590.97
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2020-09-10 13:48 BST+0100

 

[jay32267]

The bearings are probably worn and once in a while the fan jumps out of the normal groove and you get the noise. Many times tapping the fan will get rid of it temporarily but eventually the fan will either get so annoying you can't stand it or it will stop spinning.

 

[barnyard80]

Oh dear. It is a new fan!

Well, I don't know if it is genuinely new. But I purchased it direct from Noctua (via Amazon) and only received it a few days ago.

 

[jay32267]

Oh dear. It is a new fan!

Well, I don't know if it is genuinely new. But I purchased it direct from Noctua (via Amazon) and only received it a few days ago.

Well...I'm not shocked a new fan would make noise. Fans are pretty cheaply made items.

You could run with it for a while and see what happens. you might get lucky and it goes away.

 

[barnyard80]

It's a Noctua. It should be amazing. But I've had bad luck with them.

The first AF15 on my U14s heatsink made a scratchy noise at high RPMs.
The first couple of AF14 fans came in damaged boxes and Amazon LPN stickers (denoting they were 2nd hand).
2nd batch of AF14 fans have been working for a few weeks fine.
3rd (current batch that I'm having the issue with) batch has this issue.

I'm not keen on returning them, as last time that involved a hunt around for a local courier place that wasn't closed due to Corona.

 

[jay32267]

From what I've seen, Noctua is generally pretty good quality...but I think the bottom line is...pretty much all fans are pretty fragile and inexpensively made...even the better ones...and I'm not surprised that a new fan out of the box makes noise once in a while.

 

[Phaaze88]

The first AF15 on my U14s heatsink made a scratchy noise at high RPMs.

Did you mount 2 fans on the NH-U14S? If so, remove the rear fan - that's what's causing the 'scratchy' noise.
NF-A14 and A15, from my own personal testing, do not like being used as pull fans on heatsinks.

 

[barnyard80]

Did you mount 2 fans on the NH-U14S? If so, remove the rear fan - that's what's causing the 'scratchy' noise.
NF-A14 and A15, from my own personal testing, do not like being used as pull fans on heatsinks.

Apologies for my poor communication.

The NH-U14S had a single stock fan on it when making the scratching noise. It appeared to happen when the fan duty was 80%-100%. I managed to get it replaced, and the replacement was fine.