Aurora R4, motherboard diagram to ID fan and cooler

Do a web retailer search for the following =
RJN3M = 12V flextronics memory fan

The one that was on eBay just sold today, hopefully it's u that bought it

There is no part# for the chipset heatsink-fan

The fan is removed w/ three screws, the heatsink base removed w/ push-pins

If a fan can be found with the same triple-hole mounting off-set, u might get lucky  

User 'PropelDragon' in the Arena forum suggests it might be a 35mm fan, & if u can not find a suitable original  part, then replace it w/a 40mm ENZOTECH SLF-40

If a new heatsink base is used, be sure it has thermal grease / thermal paste underneath it (pre-applied from factory, or buy & apply it yourself if it's bare) before u install it (Arctic Silver 5 minimum)

"I had fans on my Gigabyte gtx1070 fail."

For purposes of full disclosure - is that the same 1070 that I thought you mentioned last month failed after the re-paste?  

If you remove the fan by removing the 3 screws, and measure the triangle as described here, you might be able to install just another fan: https://www.aliexpress.com/item/32860715088.html?spm=a2g0o.productlist.0.0.1f3e3930DsvKcf&algo_pvid=c285e18c-63ef-495c-8fcd-7a964af2d8c5&algo_expid=c285e18c-63ef-495c-8fcd-7a964af2d8c5-0&btsid=0bb0624416177672280956657e487b&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Just not that one because it's a 2 wire fan. But they make there in 3 wire also.

Also, if you remove and check out the bottom of the fan, you should often be able to find a model number or at least some specs.  Might help narrow down the search just a little so you can find them online.  Example:  

This is one of the reasons why I try to stay away from any kind of fans on a motherboard. It's all great until it fails and you have to replace it. Then the hunt for a compatible fan starts.

I had fans on my Gigabyte gtx1070 fail. Finding those was super difficult, but I found them on Aliexpress. They have all kind of OEM fans and stuff for sale that OEM's use in their builds.

Changing fans out might not be as easy as it looks.

If you are looking at the Enzo fan, I would get the cheap knockoff. Way cheaper and likely will work ok. : https://www.aliexpress.com/item/1005001615729551.html?spm=a2g0o.productlist.0.0.6d283930F6DMUH&algo_pvid=1aa6a724-2260-4ee7-a74f-5a1052dc4bef&algo_expid=1aa6a724-2260-4ee7-a74f-5a1052dc4bef-11&btsid=0b0a556516177666519032056e0ace&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

Sadly it was not me that purchased the one on eBay I didn't see it in time.

Thanks to everyone that replied I will see if I can remove the fan and measure the three points and see if I can get an aftermarket replacement.  I will let this forum know if I manage to get the system back up and running or if it is not coming back.

A couple of things ...

Is fan completely clean? Dust can weigh-it-down.

You can sometimes "service" these fans. Clean blades, then a drop of (proper) oil on bushing/bearing.

So, how hot is heatsink even getting without fan turning? I wonder if heatsink is doing most of the work here.

Hello, 

Yes, the fan is clean, with no dust that I can see.  But I have not yet removed it from the heat sink, so there could be dust under it, but it moves when blown.  It just ticks when powered, left and right at two-second intervals.  I have been looking at the after-market solutions, problem is that they are all too tall, so still looking.  The video card is right above the fan and heat sink. I only noticed that this fan was not working as I am trying to replace the other fan that sits on the heat sink above the processor, as I am getting system fan failures when testing.  I can't find a replacement the same size 50mm x 10 mm with 3 pins for sale in the UK.  I have one on its way from China

Once I have replaced the CPU fan.  If I can't get a replacement for the little fan on the heat sink. I will try the system to see if it does indeed need it or not.  AS it is still cheaper than a replacement reconditioned motherboard