Abnormal temperatures with H100i V2

Hello! I'm currently using an H100i V2 I bought a year ago. I have had a couple of problems with it. It's idling at 30-35º (was 23-25º when it was new) and under full load it ranges from 45-75º (depending on the test software I'm using). The first time I noticed this problem was a two months ago, when I installed it after a cleaning session, my CPU was idling at 45º and 85º on full load. I read that it may be an issue with a bubble, so I take it off, moved the tubes around, same with radiator and it kinda fixed itself. A couple of days ago, all my fans went to 100% and I had to open the case to check if everything was working correctly, one of the tubes was super hot and the other one was cold, not even close, opened RealTemp and it was showing 65º out of nowhere. I shut down the pc for like 15 minutes, re-checked the tubes and stuff. When i turned it on, it was normal (25-27º), but now it's idling at 30-32º again. Obviously something it's not working properly, and that's strange, because I reapplied thermal paste two days ago (Cooler Master high end, can't remember it's name atm) My rig:

- i5 4690k (Stock)

- Asus Maximus VII Hero

- Nvidia GTX970 Gaming G1 (21º Idle)

- NZXT H440 Case (Stock fans)

My questions:

1) Is this normal with AIO coolers?

2) Should I take it to the store where I bought it or should I send it directly to Corsair (RMA)? I'm from Peru,btw.

3) If the RMA process is possible, do I have to pay the mailing costs? How does it work?

4) It is normal that one of the tubes is warmer (sometimes a lot) than the other? Or both should stay at the same temp? Kinda confused about this.

Thanks in advance!

1) No, not normal but it does seem to be an occasional problem on the H100i GTX/v2. It is possible "bubbles" are restricting flow, but normally you get some gurgle and grindy pump noise to go with it. It also should have less effect on CPU temps. It is more likely some particulate build up in the coolant stream that is normally settled, but becomes disturbed when you take it down to clean, move the case, etc. Before it settles down, you power on and it moves to some place where it can be more harmful, like the pump entrance/exit.

2 & 3) Yes, you should replace the cooler and this is not how it is supposed to work. I do not know which is the best option for you or the Corsair protocols for Peru. You should start the Tech Support ticket from the link at the top of the page and then try and investigate your options while waiting. Unfortunately, other than walking into a local store and grabbing another, this tends to create down time. These days, you more or less need a back up cooler. If you don't have one, this might be the time to pick one up and use or replace the current model, then RMA/exchange the H100i v2.

4) Yes, it is normal for the outflow tube to be warmer than the return hose, which releases heat in the radiator before returning to the CPU/pump for another trip. How much heat is released is both fan speed and radiator surface area specific and it's hard to give you a number. I know mine (more or less) from using thermal imaging. Generally, you are talking about a couple of degrees Celsius difference and no cooler can take all the heat out in one pass. So, it should be "I think this tube is warmer" and not "Wow, this tube is hot and that one is cold". The latter suggests a problem and I think you have a partial flow restriction of the type described above.