Thanks for the reply!

The 80mm is the Noctua fan I meant. I won't buy that as you suggest. There seems to be a 2018 version of the Corsair H75 and a newer version. Would either work? Is the ML120 pro essential or will the computer work with the stock fan and H75 in Corsair's intended configuration just showing an error message that can be ignored?

I read if some other posts that there is an alternative configuration that doesn't use the Y splitter and avoids the error.

Is this the ML120 PRO you mean?: https://www.corsair.com/eu/en/Categories/Products/Fans/Magnetic-Levitation-Fans/ml-pro-config/p/CO-9050040-WW

In general the current configuration works fine, it just sounds like a vacuum cleaner when the CPU is under load.

@r72019 :

Dell does not sell the 9900k in the aurora r8 without liquid cooling.  If you got it that way stock it was a manufacturing defect and you should contact Dell to have them fix their error at their cost.

Maybe @MysteryMedic bought it from 3rd party seller like BB or Amazon? Or config could be different outside of the US? I'd say, if he did pay for liquid cooling, then yes, ask for the remedy. Else, let's all in case it turns out he got a K processor for free.

Also the corsair h75 2018 is the newest version.  It has a newer pump plus the aio block has white rgb leds.  

Dell does not sell the 9900k in the aurora r8 without liquid cooling.  If you got it that way stock it was a manufacturing defect and you should contact Dell to have them fix their error at their cost.

Checking my system information it looks like the PC has the standard i9 9900 rather than the 9900K. When ordering it I thought I had selected the K version even though I didn't get it factory overclocked but this looks like my mistake. I am based in Europe and the Dell website for the product has now changed a lot (no more r8) so I can't go back and check if it was advertised as the 9900 or 9900K on the configuration I eventually selected. Either way I don't see myself doing anything to actually be bottlenecked by the CPU for the foreseeable future so I don't really have a reason to overclock.

Regarding the H75, corsair advertises two versions:

https://www.corsair.com/eu/en/Categories/Products/Liquid-Cooling/Single-Radiator-Liquid-Coolers/Hydro-Series%E2%84%A2-H75-Liquid-CPU-Cooler/p/CW-9060015-WW

https://www.corsair.com/eu/en/Categories/Products/Liquid-Cooling/Single-Radiator-Liquid-Coolers/Hydro-Series%E2%84%A2-H75-%282018%29-Liquid-CPU-Cooler/p/CW-9060035-WW

I would guess the 2018 is the current one as Beryllium suggests and the appropriate one for this PC?

An alternative configuration would be use the top stock fan with the radiator instead of the ML120 PRO suggested above although I would expect this to be more noisy/maybe not work.

Thanks, that makes sense, probably would just mean my computer would start sounding like a vacuum cleaner a bit later if I kept the OEM fan then.

I found this video describing the installation procedure for the H60 in the R7:

https://www.youtube.com/watch?v=RC9Nk0yT8bo

Would the only real difference in installing the H75 be that I would have 2 power cables to the Y adaptor (for 2 fans) + 1 for the radiation and otherwise installation would be much the same? Any tips/things to watch out for when actually putting the AIO in?

Once the AIO would you be able to recommend a guide for configuring software to work with the new fan or should it just be plug and play?

I know this thread is old, but what did you wind up doing? I also have an R8 without liquid. I don't wanna take the Mobo out do I'm thinking of just getting a better fan for CPU. Any advice?

H60:

You don't need to remove the mobo to install the h60 or h75, new or old version.

The R8 comes with its own bracket (regardless whether you got air cooling or liquid cooling).  It has the same thread as the Corsair H60's bracket.  That's why you don't need it.