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TL;DR Putting space between intake fans and their dust filters seems to substantially improve airflow and combined with them being closer to components seems to improve temperatures too.

My case is a Silverstone Primera 02 (SST-PM02B) which I love despite it receiving a largely negative review from Gamers Nexus.
It was my choice for it's plastic-less design, inclusion of/support for 140mm PWM fans, glass rather than plastic side panel, spacious interior and USB 3.0.

However like a lot of cases it detrimentally concedes to supporting the travesty that is an intake-mounted radiator (bringing heat from components at case rear to the front only to blow it back in towards them :eek:).
Or more likely it uses tooling from a case that had 5.25 inch drive bays which they're up-selling as providing radiator support ;)
The result is a load of unsightly empty space and the front/intake case fans being far from the components they are trying to cool.



I decided to commission a local 3D printer to make me a set of fan spacers for the three intake fans.

Sticking a ruler in my case I figured 80mm spacers for the top two fans would be safe clearance-wise and affordable-enough. The bottom fan sitting as it does in a PSU shroud cut-out could only be brought forward 40mm.

Unfortunately/fortunately the fan spacers (or at least the model they modified) are 145mmx145mm and so all three stacked would not fit at the front of my case.
But then I realized that the bottom most fan is really blocked off and only cools the hard drives anyway:

So I moved the lowest fan to above the CPU as an additional exhaust and reinstalled the top two intake fans using the 80mm fan spacers

I had previously already blocked off the front portion of the top vent and the PCi-e cover grills below the GPU with cardboard

As you can see from this photo (click for larger), the lower intake fan nicely lines up with my the horizontal (i.e. front-to-back) grills on my graphics card.


Now I did consider doing some rigorous testing taking temperature readings before and after installation but
  1. I couldn't be bothered
  2. I wanted to start using the new cool thing A.S.A.P
  3. The fan settings I chose could easily skew the results
I'm also glad I didn't as the results would be rendered obsolete by the relocation of the bottom intake fan anyway.
But anecdotally the difference is really significant
  • Can really feel the suction/airflow putting my hand in front of dust filter when couldn't much before
  • Holding a incense stick in front of the dust filter the smoke is sucked in vigorously from over an inch away
  • I maintained a GPU junction temperature of 29°C-31°C the whole time writing this post (including image manipulation) with the GPU's own fans NOT SPINNING. I have the fans set to kick-in at 38°C and shut-off at 30°C and typically after an hour or two the temperature would slowly build up to 38°C at idle. It's very unlikely you'd be able to achieve this with a vertical-grill GPU cooler but with horizontal, air from my case intake fan is actually blowing the length of the graphics card and exhausting out the GPU's built-in functional exhaust. You could likely enhance this effect further with some ducting
  • Again while writing this, CPU temperature has been hovering between 25°C and 26°C. In my tweaking I turned the CPU fan down at idle and I have the two exhausts super low at idle and lower than the rear exhaust was set before. Idle temps previously were 28°C-32°C or so.
  • Although really hard to quantify, I feel that dust is building up faster - especially considering it is now spread over a larger area and not in a defined ring like it was before
Now I will admit that we're talking January in England here. Our central heating maintains 16°C 24/7. But the improvement over previous temps is still pretty good.

I'd heard talk that dust filters create turbulence and diminish the effect of fans when in close proximity but I didn't expect the effects to be so drastic.
This could be a big development in case air-cooling performance. Setting the fans away from the front removes the need for a mesh/finger guard so you can just have a dust filter with no further obstructions.
It also allows the use of superior, soft nylon filters (like the DEMCiflex Dustfilter Set for 420mm Radiator I use over my intake fans) without airflow-blocking rigid supports (like the case's original dust filter).
Before the spacers I had to carefully tease the dust filter after every clean/replacement to stop it rubbing the fans.

Hope this provokes discussion and ultimately leads to performance-focused improvements in case design.

Here is a Google Photos album of the full res photos for easier browsing.

Some relevant notes regarding my case I missed:
  • I removed the stupid LED projector from the case immediately after unboxing it. It's just two screws and removing it makes cleaning the dust filter much easier.
  • I used to keep taking the front panel on-and-off but for some time now I have just left it off. 2/6 of the ball joint connectors that keep it on broke and it's just arduous to take off. That obviously leaves it a little ugly but airflow is likely a little better.
 
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Fan shrouds/spacers have been known to increase performance in some cases. Not a new thing.

Aware it's not a new thing but it's not discussed/tested much anymore and not something case manufacturers have cottoned onto yet.
Admittedly I may have missed some discussion as I have been calling them/searching for 'spacers' rather than 'shrouds'.
Searching now it seems they were mostly a water-cooling thing and are no longer available to purchase. Overclockers have one in the "Old Water Cooling" category but it's only 120mm (which makes sense as 120mm fans have better static pressure for pushing air though a radiator).

Research you linked is thorough and interesting but is specific to radiators - not dust filters.
 
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Research you linked is thorough and interesting but is specific to radiators - not dust filters.
Whilst your statement is correct, I'd like to suggest that the principle is the same. Ie a restriction in the airflow - which is what radiators and dust filters do ;)
 

Stu

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