Time to hit the punch list.
First and comparably low hanging fruit is tackling GPU RAM temperatures -
and whilst taking things apart, replacing the insufficient Displayport extension with the one you see at the right edge of the photo: The PCB contains an active signal rectifier which promises to deliver full DP1.4 bandwidth. We shall see!
As I want to avoid taking the water loop apart at all cost (getting it drained, filled and reasonably air free is a PITA in a reservoir-less build - for that alone quick disconnects are worth a consideration), I disasseble the 3090 in situ...
...revealing my previous layout of layered 0.5mm pads. As you see from the traces on the backplate, they made reasonably good contact, but I hope to improve things a bit by using 1.5 mm Gelid pads.
Setting them aside for later use...
...I place the Gelid pads using this template
here, promising to cover all remotely relevant components, and assuming that the pads coming with the Corsair block are not the problem's cause - and as you can see above, indeed I appear to have forgotten to peel off the protective film on one of the layers when stacking the 0.5mm pads in my previous iteration.
That was pretty straightforward...
Now, replacing the DP extension without taking the water loop apart is a bit more challenging as the cables are placed under the tubes.
Propping it up with some good old lego parts...
...I somehow manage to get it out without causing a flood...
...and replace it with the revised extension...
...that not only comes with a pretty prominent PCB (well, given how spatially constrained this build is, any part looks big), but also with significantly improved
blackness.
Unfortunately though, said PCB buys me a clash with my tubing,
...but flipping the DP connector around (shifting the PCB to the bottom side of it) solves that...
...and gets me to a pretty tidy package that should be able to plug in my Reverb G2 without taking the case apart.
Two of three boxes ticked - remaining issue is getting the PSU's temps under control, with virtually no space for additional fans, and little appetite for getting back to the high pitch of high performance 40mm fans.
@Vaderator 's water cooling approach is pretty impressive (didn't someone recently ask jokingly whether anyone water cooled a PSU yet? Well, I guess it has been done), but looking at my components and the temperature equilibrium I have found, I'd like to avoid any additional heat in the loop, so I'll try to keep sticking to air.
The idea is to use bleed air from my main fan to assist in venting the PSU: It's an approach similar to how planes before the 787 would bleed air from the jet engines to drive the cabin ventilation system, avoiding the requirement for additional fans and heating. This approach has been dropped in recent engine designs to increase fuel efficiency, but as the Noctua Industrial's performance is clearly not what bottlenecks my build, I'm not too worried by taking a few percentages off its drag.
But before I cut my main fan apart, I take the 40x10mm Delta screamer I have been using in the first iteration of cooling the PSU...
...and mod it for a proof-of-concept:
Cutting away about this much of the frame and ducting it...
...should lead to a zone with negative pressure at the fan's periphery, allowing me to suck some hot air out of my PSU, and to eject it to the top together with the exhaust heat from the radiator.
This prototype should be pretty representative of what I'm trying to achieve...
...and after hooking it up to a PSU I'm ready to test my plan:
Aaaand:
BINGO!
With that established, I can start to scale things up for my build:
Whilst fan and PSU are in perfect position to connect their air flow, a first thing to fix is reversing the air flow in the PSU as directed in the wrong way: I want to maintain the Noctua A4x10 to assist the main fan, not to work against it.
That means detaching the PSU from the frame...
...and taking it apart:
Rather annoyingly, the fan is screwed in from the inside, so in order to flip it around...
...I need to dismantle the entire PSU.
Reversing the fan is comparably simple, and after re-assembling the PSU, I should get something that works with the intended peripheral flow of the main fan:
The mod to the 140mm fan will be slightly more substantial:
The line sketched onto the frame indicates the tangent point of the PSU's airflow vector and the fan's duct - that's where negative pressure should be highest and where I'd want to start my duct.
A little dremeling later, I get to this "window" in the frame...
...and build up a duct using PCB sheets to direct the airflow as required.
The u-shaped slot is to pass through the AC power feed, as it will need to connect through the ducted zone.
Before re-installing the PSU,
...I replace the original 0.25mm thermal pads I have been using to connect PSU and front heat sink, as they have no trace of ever having made contact: Looks like I have been cutting them too thin. That's a great use for the 0.5mm pads I have been removing from the GPU earlier on, and two layers of them should make sure that there is good heat transfer going ahead.
Also, note the insulation tape around the PSU's AC end - I use it to air tighten the case and leave as little a gap as possible between ducting and PSU.
With that done...
...the PSU can go back onto the frame, and all that's missing is a little PVC flap to form the duct's top face:
Sealing it onto the fan using double-sided tape and some insulation tape to stick it to the PSU, it should make for a sufficiently tight containment.
Stress testing the setup using the games that made it shut down previously...
...I get to sufficiently reduced temperatures at the PSU's hot end, so it seems to work out.
As a final tweak,
...I apply my remaining pack of Gelid pads to the underside of the case's top cover to make for better heat dissipation from the GPUs back side.
Job done! Left, my 8700k/ 1080 air cooled S4M, right the current gen build.
The layout also works vertically, as the "left" short side of the build has no airflow requirements and can be used as a bottom face without compromising cooling:
Overall, the "bleed air" approach to cooling the PSU slightly increased the temps in my loop, as the PSU is now blowing hot air against the radiator, rather than away from it. Adjusting my radiator fan curve slightly dealt with it, and some further tweaks to it were required to get the PSU airflow to a level where it would not trigger any thermal shutdowns - below you see the before-and-after curves, and with the latter, I'm now looking at a stable system at any load I could come up with.
And: The Displayport extension now officially does VR!
I'll eventually want to replace my CPU with one that works as advertised without tweaking it, but as I have working settings now, the pressure is off somewhat... so for now I call this build “done”.
Thanks for all the feedback and advice received- this site is a really inspiring place for anyone trying to develop something off the beaten track!
