Noisy CPU Block?

Ok basically I've had this computer with a custom loop up and running for almost a year. It's been great, generally speaking quite quiet. It's never been amazingly quiet though, which is something I wanted from the start. Now I've got some time on my hands I'm seeing what I can do to make it quieter. The CPU block (a Aqua Computer cuplex kryos HF I beleive) has a sort of hissing sound? I assumed at first this was normal but am rethinking now, its quite audible, particularly compared the GPU block which is completely silent.

They're both in the same loop, with a pretty standard pump, reservoir and 360mm rad. This may well be just my imagination, but I've never actually seen another custom loop like my own so I have nothing to compare it to.

Any of you guys have any insight into what it could be? Or even better had the issue yourself and fixed it?

Cheers

Probably time for a cleaning if you've had it running for a year.

At least a yearly cleaning is good practice.

Its been cleaned recently! I cleaned each block and replaced all the fluids about a month ago or so, constant hissing is still there

I got a penny (which if you win you will find in a couch cushion in your house or apartment) says it's cavitation created by excessive water flow and higher water temps allowing the air in the water to separate under pressure of going through a more restrictive block. I think I covered all my bases in that one bet . Pictures and more information will be needed, people here like pictures

Could be air bubbles trapped in the CPU block.

Had a loop do that once. Had a mini vortex in a fitting as it entered the GPU block. Slow the pump down, squeeze the hose to change flow to push the bubble out etc. It should dissipate. There is a pic somewhere here of the mini vortex in the tube but that was over 5 years ago methinks.

Ok you wanted some pictures, heres a picture of the full loop



And a picture of the CPU block in question.


I beleive you guys are probably right, and squeezing the tube makes the sound go away but it continues the moment I stop squeezing, I tried giving it a shake too but if there are bubbles they dont seem to want to dislodge.

- - - Updated - - -

Apparently full loop picture hasnt added. Here it is again.

I'd also advise on some angled fittings. Should help you get rid of the excess tubing and give better case airflow.

As for the colored fluid, hope you've done frequent maintenance or it can stain and possibly clog your gear.

Yeh it does look a little cluttered, I've been planning on 'upgrading' to the rigid tubing for a while now, but when I can afford it. And unfortunately I wasn't aware of dyes clogging when I got it but I have replaced the fluids entirely every 4 months or so.

While it's running tilt the case towards the back of the mobo. You should be able to go pretty far, almost horizontal. Make sure the res is very full and the res top fill is tight. Might ned to leave it at a 45 deg or more angle for a while.