I've been doing more templates for the fan cutouts with the intention of cutting the holes at the same time as the PCIe slot and it forced me to think more about the PSU options.
If I can successfully make the TEC heat exchangers and install the TECs then the total power requirements are really going to be pushing the limits of a 750W PSU even if I only use 6V on the TECs. I'd much prefer overkill for the PSU since it's one less thing to worry about from a stability point of view (there are also some minor efficiency and lifespan benefits from running the PSU nearer the middle of the power range rather than right at the limit).
I had previously wondered whether I could fit an extra PSU for the TECs but for some reason came to the conclusion it wasn't possible. I think because I hadn't yet considered the option of moving the bottom radiator forwards a bit and placing one sideways.
Anyway, I tried again in the model and it turns out that it is sort of possible to fit two SFX PSUs after all:
(Since I don't have access to a real one, I created the textures for the model of the SF600 from photos from this review https://smallformfactor.net/reviews/powersupplies/corsair-sf600-review-new-player-joined
so I could see where the modular connectors would end up --- Thanks)
It would be necessary to place the PSUs up to their respective outside edges of the case in cutouts in the side panels in order to get just 18mm space for the modular connectors of the PSU used for the computer. The PSU used for the TECs would have the 24 pin ATX, peripheral and one of the PCIe connectors blocked by the 240 radiator with only the CPU VRM power and 2 of the PCIe connectors accessible. A non-modular PSU (like the one I have) in that location would work though or it would be possible to open up an SF600 and solder some custom cables in place of the modular sockets perhaps.
It's not totally clear whether it would be best to arrange the PSUs fan up or fan down. I was previously planning two 80mm side fans in those locations, one inlet and one outlet to get more fresh air flowing towards the GPU and up through the HDDs. In the new configuration I think at least one of the PSUs - probably the TEC one - ought to be fan up to maintain the airflow through the case. The connectors and the power inlet on the other PSU work better if the PSU is fan down but for a blower GPU or a watercooled GPU I think it might be better if both PSUs were fan up, again to increase airflow. There would be three inlet 120s restrcted by radiators, a push pull outlet 120 pair restricted by a radiator plus two outlet 92mm fans restricted by the PSU components. There's space for one more 80 fan which could be another outlet as long as that wasn't too much for positive pressure to be maintained inside the case.
This is quite a big change to the current design and would require some rework of the rear panel. It only makes sense if I can make the TEC exchangers. Without the TECs, I'd prefer to stick with the current single PSU design. So, after I've finished the PCIe slot I'm going to need to attempt the TEC heat exchangers to work out where the design is going next.
Some more shopping:
A coping saw (143.9 RMB) for cutting the PCIe slot and the fan/radiator cutouts in the case. The hole cutter I have is too small for the fan holes which aren't circular anyway and the coping saw should be an improvement on the hacksaw for this task.
A small cross vice (480 RMB) for my drill press so I can drill the copper pipes accurately to make the TEC exchangers. It's pretty hard to drill accurately into the side of a tube without something like this (I'm reminded of the lathe my father gave me for one of my teenage birthdays which I used for this task once when making a mechanical balance. I've hung on to it for 30 years but it's currently in storage in the UK and isn't likely to make it out here to China) and the pipes need to be aligned as accurately as possible so the plates lie flat across them all and the solder joints are thinner for better heat transfer. I don't expect the heat exchanger to work exceptionally well but there is quite a lot of area compared to the sum of the CPU heatspreader and GPU die (about 3X for the cold side and 6X for the hot side I guess) so the heat flux is relatively low and I think it will be good enough. I might try squashing the pipes a bit to get more contact with the plates. Also M12 nuts and bolts (5 RMB).
A 200W soldering iron (180RMB). Hopefully I'll be able to successfully braze the pipes carrying the liquid together so I'll get a reliable water-tight system but I don't think the torch is going to be powerful enough to braze the pipes to the plates. I think I'll probably have to do that with solder.
I also bought a full cover clear face mask (68RMB) to protect my face when brazing. I already have leather gloves and a cotton coat.
I picked up the little torch. I may need to find a local place to refill it with oxygen --- it's not allowed on the metro so it was a 50RMB taxi fare to get it home.Edited by heb1001 - 8/5/16 at 9:34pm