Next and rather substantial chapter: Fan-Off!
The vanilla 90mm fan coming with the otherwise rather amazing Gigabyte 1080 mini has to work quite hard in my compact configuration - and the fact that the shroud forces half of the air directly against the HDPLEX with a small gap of 1.5mm not really making for an escape path certainly contributes to it.
Result is a pretty audible stress noise level, and I suspect that some of the high temperature readings I get on the HDPLEX may be owed to the GPU acting as a hot air blower aiming straight at it.
So: Plan is to significantly increase the fan diameter to bring RPMs down, and to modify / improve the airflow within the case by removing the shroud of the GPU - pretty much like in the eGPU version of the 1080 mini which gets stellar reviews for noise and thermals.
My CAD model (see first post) indicates that I will have a maximum of 13.6 mm to play with between case lid and the naked GPU cooler (and that only in the centre - the radiator has a stepped surface to neatly fit the standard fan)- so I have lined up two candidates that would potentially fit in after some modding:
Plan A: A Noctua NF-A12x15 PMW slimline 120mm fan with 15mm frame thickness - acoustically most promising but already known to not fit straight-out-of-the box
Plan B: The Cryorig XT140 slimline 140mm fan with 13mm advertised thickness, potentially giving me a little more headroom over the chiller, and even more air - and from what I figure pretty much the biggest fan that can go into an S4M.
The Noctua delivers a predictably impressive unboxing experience - remarkable given that we are talking about a £15 part...
The box contains all sorts of adapter cables and a set of rubber bearings - unfortunately, the one thing that would have been really helpful, an adapter to hook it up to a GPU header (a smaller form factor than a mainboard fan header) is not included... so we will be in for some soldering later.
The Cryorig XT140 is well, but not as neatly packaged, but for what it lacks in wrapping, it makes up by its sheer dimension and ...blackness. It looks rather impressive, and at this point I consider to prefer it just for that reason!
Accessories are comparable to the Noctua (apart from the Noctua-only low noise adaptor), and again, no GPU header adaptor included.
Both side by side for a direct comparison:
Now, checking dimensions, comes a bit of a surprise:
The Noctua is pretty much 15mm thick as advertised...
...the Cryorig, however, is really 13.5, not 13mm thick - doesn’t sound like much of a difference, but in my case this might break things.
Placing the Cryorig over the GPU also shows a second issue: It will need a pretty substantial mod for the frame not to collide with the HDPLEX, and a rework of the 120mm SkyBracket in order to move it further to the bottom of the image to avoid a clash between the fan blades and PSU.
The Noctua looks more promising: The fan stays clear of components other than the GPU; challenge will be to mod the frame to fit in approx. 13mm clear height (which should be possible as the actual fan has about 2mm of structure underneath connecting it to the frame).
Next step is getting the shroud off the GPU- and in an ideal world without obviously voiding the warranty:
In absence of finding any teardown vids or documentation it took me a while to identify the 4 self cutting screws that secure the shroud against the radiator block. They are accessible to the side openings and come off very easy, allowing for a completely “traceless” shroud removal.
(2 more screws in same position on opposite side)
With the fan cable pulled off the header, we get a first look at the “naked” 1080 mini:
With the card back in the case it confirms some of my earlier observations:
Both Cryorig and Noctua clash with the cooler despite the Cryorig being nominally slimmer...
With the Cryorig presenting the additional challenge of having to work around the PSU.
It looks pretty rad though...
Looking at where the Noctua clashes, it should be possible to address the key issue, which is the “deep” part of the cooler colliding with the frame, by trimming it back, with the actual fan spinning just about collision free in the “shallow” part of the radiator. Tight, but not impossible.
As in both cases I’ll need to mod the frame, I opt for the Noctua giving me the predictably better acoustic outcome, leaving the Cryorig as a plan B in case airflow requires increasing.
Hypothesis on airflow is as below:
With the fan pressed flush against the case, I can assume that it pushes only outside air against the GPU,
The removed shroud should lower air resistance on the read end of the case and allow more air to escape on that end, taking hot air off the HDPLEX and allowing air to escape pretty much through all available openings on the rear, side and top (whereas the shroud directed air exclusively through the rear and front ends of the card - with the front end blocked).
Looking at the clashes between the fan frame and the radiator, I will need to cut pockets taking about 3mm off the frame...
...and get rid of one of the five spokes holding the motor.
Time for some (messy) Dremel action!
(FAST FORWARD) After a few iterations and some more vacuuming (that stuff is nasty...) I get to this state here with pockets as sketched above on both sides - and a motor that is pretty self-confidently anchored by four of five spokes only.
The frame fits *perfectly* between bracket and case, and *just about* hovers above the radiator...
with even a little torsion to the chassis already clashing the fan (luckily the S4M is rock solid when all panels go on - thanks
@Josh | NFC for an amazing design) - so I guess it’s fair to call this an *extremely* lucky fit with the moving parts having < 1mm tolerance between case and GPU radiator.
Phew!
Last bit is soldering on a salvaged 4-pin connector for the fan header (not easy to get by in that size... with that said, an hour later I noted that there was one included in the HDPLEX DC-DC connector kit - guess I have one spare now
)
Clear upside is allowing me to trim the power feed to just the length I need in line with my “no excess” cabling policy.
So, that looks like a job done, pending firing it up...
...and: Bingo - all spinning happily!
And whilst the Cryorig really looks impressive, the consistency of the Noctuas on both side starts to grow on me.
Stressing the machine I can confirm that noise levels have improved significantly - even under full load it’s barely audible with no motor noise whatsoever and only a light white noise from air flow.
And the thermals are working out much better: After getting a bit competitive when looking at the
PPL thread, I have started to overclock the build, pushing it quite a bit with the CPU at nearly 5GhZ and the GPU bang-on at 2100 MhZ core speed - the GPU stabilises around 80 deg C on full load and with all panels on in horizontal position, and most amazingly the HDPLEX is 10 (!) degrees cooler as compared to the previous configuration (GPU shroud on, default GPU fan and no overclocking).
This would confirm that the heat issue I had with the HDPLEX didn’t really come from CPU power drag - but rather from the 1080 permanently torching it with a constant stream of hot air...
More testing to come, and most importantly: A proper front bezel design!