Cooling Does Fan Clearance Matter for Radiators?

[kodakrome]

I'm very slowly dreaming about a watercooled SFF. Love the stuff shown on the forums and elsewhere, but I keep wondering if fan clearance matters. Sometimes I see a radiator setup with 15mm fans where 25mm could fit. Both are obviously tight, but how much intake clearance do you really need? Is there a point that the shorter fan outperforms the taller one due to clearance?

 

[BaK]

Thanks to @K888D, you may find interesting data here:
http://www.lazer3d.com/2017/02/05/fan-performance-testing-part-1/#1

 

[kodakrome]

@BaK , thanks this is what I was looking for! Sorry to snoop, but I see from your M1 build that your bottom radiator does not have very much fan clearance. Do you still find it useful? Thanks again.

 

[BaK]

My thinking was that one more rad won't hurt, but can't tell more unfortunately as I didn't check the temps without it.
It may help, but only a little because of the low clearance as you noticed, and furthermore because of a slim fan running slow to be kept silent.

All in all I think it is more there to fill the space available and to help accomplish a clean custom loop (I really dig the hard connexion with the GPU)

Anyhow after almost 2 years I never had to complain about temps on this build.

 

[kodakrome]

@BaK thanks for the info, yours is one of the few builds I've seen with the radiator connections placed toward the rear and it does seem to work really well (and look awesome) as you said.

I was leaning toward the Black Ice Nemesis GTS @ 30mm tall + Noctua 15mm fan, but the lazer3d article made me think maybe the XSPC TX series radiator (20.5mm) could buy that extra cm of clearance.

When comparing radiators the GTS obviously specs with higher capacity, but no one is benchmarking radiators in such a confined space.

I would like to put a side radiator in as well. General thinking seems to be: get the biggest radiator you can fit and tuned to your desired fan speed. But that will also sacrifice fan clearance.

 

[BaK]

@BaK thanks for the info, yours is one of the few builds I've seen with the radiator connections placed toward the rear and it does seem to work really well (and look awesome) as you said.

Just keep in mind this location could be troublesome if you need to fix something...

I was leaning toward the Black Ice Nemesis GTS @ 30mm tall + Noctua 15mm fan, but the lazer3d article made me think maybe the XSPC TX series radiator (20.5mm) could buy that extra cm of clearance.

When comparing radiators the GTS obviously specs with higher capacity, but no one is benchmarking radiators in such a confined space.

GTS + slim Noctua, XSPC + regular 25mm fan or XSPC + slim Noctua... hard choice!
I think I would go with the slim combo as efficiency, in a short clearance range, seems to be highly increased for each added cm:

I would like to put a side radiator in as well. General thinking seems to be: get the biggest radiator you can fit and tuned to your desired fan speed. But that will also sacrifice fan clearance.

For a side radiator, with positive pressure in mind, a pull setup is recommanded for fresh air and easy cleaning (dust on the rad instead of inbetween rad and fan).
So the intake clearance is not impacted with the rad thickness, the output is though.
That is not covered in @K888D 's test (in part 2 maybe ; ) , but obviously the output distance to a flat surface is also impacting the fan efficiency.
If you are talking about an NCase build, I would at least keep some clearance between the fan+rad and the PSU.
(I have around 1cm with my push/pull setup and that seems enough)