Hi everyone, I rebuilt my loop about a couple of months ago in order to put my GPUs in parallel. I have done everything by the book, compression fittings, leak test, etc However I am noticing that I am losing coolant very slowly. Something like 1mm a week and it's pretty consistent. I placed white towels everywhere (the coolant has a red dye) and they all came out clean. Yesterday, I forgot to update my fans profile before firing Far Cry 4, after about 20 mins the GPUs overheated causing a blue screen and as the computer rebooted I saw bunch of bubbles coming up the reservoir. I panicked, unplugged the power, and checked everywhere. The back of the GPUs were very hot, clearly they overheated, and yet no sign of leak. WTF? Were these steam bubbles? What am I missing here? My loop: Pump MCP35X2 (dual DDC) Swiftec CPU block Chipset RX480 rad Triple R9 290 in parallel RX360 rad Reservoir Coolant is Halford's finest distilled water with Mayhem XT-1 red concentrate (that now is more purple than red, but that's for another thread).
Are you sure the pump is working? To me that sounds like maybe the coolant is not flowing and overheated in your gpu waterblock.
Yes the pump is definitely running. I just run my whole rig in silent mode when not gaming. All fans to 700rpm and the pump at 25%. I just need to remember to increase all this before gaming. Would love to automate it but the Asus Fan Xtra software only sets curves based on CPU temps, not GPU.
What tubing do you use? Silicone tubing is slightly porous to water molecules, which very gradually evaporate through the tubing walls. The dye molecules are much bigger so stay behind. If you use Tygon or Clearflex tubing that should not be a problem. But there could of course be a tiny leak somewhere that is so slow that any coolant leaking from it evaporates before it has the chance to accumulate into a droplet that can fall on and stain the towel. Water is less able to contain dissolved air as it warms up. The air is released as tiny bubbles which can cling to the walls of the tubes and the reservoir. As water continues to heat up these bubbles get large enough to break free and rise to the surface.
I am using the xspx tubing, it came with the XSPC360RX kit and I think I bought some extra ones from their site. Their site says it's pvc. The water is still going down, nice and slow. I think it will run out in a couple of months. Could be worth draining and changing the tubing? perhaps to some clearflex one as suggest above...
PVC tubing should be OK. I wonder if you have a slow leak or hairline fracture in your loop somewhere. May be the radiator?
I had a hairline fracture in a pump top I bought. Tiny drops started forming right in the middle of the block. It was lucky it was where it was, or I may not have spotted it. The water level has dropped a good bit in the time my watercooling has been in place. I'm fairly sure its just the angels share though. Nothing has short circuited and I haven't noticed any damp. I really need to top it up at some stage.
Check the fins on your radiators for fluid. I've had 2 RX480 rads fail on a seam in the middle. The fans were drying the fluid so it was difficult to spot initially.
Is the loop completely bleeded? Often a bit of air will remain somewhere in the loop (in a block or rad) this air might be slowly finding it's way to the res and thus giving the appearance of losing fluid, while in fact you're losing air. (Which is good.) You can test this by marking the water level in your res and then shake the case a bit to get out remaining air bubbles in the loop. Check the water level again after shaking.
Actually I just realised I put the wrong rads in the OP. It's actually AX480 and AX360. Still, they are both set up in push/pull so if I have a leak there it will be very hard, if not impossible, to spot. Based on your advice, I will leak test it for 48 hours with the pump at max and put kitchen towels everywhere conceivable. Hopefully I will get a small stain somewhere, especially if all the fans are off I'd say so, it's been running for 4-5 months now, and I topped it up quite a bit at the beginning. Now it's pretty stable and level is dropping very consistently which does suggest a leak of some sort. If the leak test shows nothing still, I will have to decide whether to keep topping up or just give and rebuild.
