i5-4690k idling at ~55C with water cooling

[NathanWolf]

Hi, and thanks for taking a look

The short of it: My system is now idling at 55+ degrees C, and I feel like it shouldn't be. Do you have any ideas as to what could be causing it, what I can do or whether this is normal? My gut says it should be a LOT lower.

Intel Core I5-4690K OC 4x4.0GHz (OC by the store I bought it from)
Antec Kuhler H20 650 water cooler
Gigabyte GeForce GTX980 OC 4GB
Windows 8.1 x64

When I bought it 5 months ago it was running like a dream, but with time I started noticing that the LED heat indicator on the water cooler was never blue anymore - it was always magenta, sometimes red - and the fan would sound like a jet engine, even when just opening Chrome on google.com, or the Win 8 picture app.
I've taken a look, and just after booting the temperature is 52-58C, and it stays there. In BIOS it's 47C. The fan pretty much never goes below 1400RPM and often revs up and down which it extremely annoying (running 40 dB at the lowest). I don't have a thermometer, but I'd say the intake temperature is not above 23C.
Playing Middle Earth: Shadow of Mordor (1080p, ultra, no cap or vsync) for 20 mins runs smooth, but the temp goes to around 75-78C.
It feels like a have a crappy stock cooler with no paste, and not a water cooler.
I've given the fan a good blow through of canned air to dislodge any dust in there, but it hasn't helped a bit.

After booting the pc, not opening any programs, killing background software, stopping AV, and waiting for a few mins doing nothing:

 

[synphul]

You could try feeling the cooling hoses, they should be similar in temp. If one is really warm and the other is cool it could indicate an internal blockage of some sort. It could also be a weak or failing pump. You can try removing it from the cpu, cleaning off the ihs on the cpu and the base of the cooling block and reapplying thermal paste. Outside of that it might be time to look into your rma options for that cooler. Single rad/fan aio coolers already perform around the level of most decent air coolers. Any performance decrease with time is going to make it worse. There's nothing to fix/replace on aio coolers which is why I suggested rma.

 

[NathanWolf]

I'm affraid it might be a blockage/pump then... I had actually felt the hoses already, but didn't know what to make of it since I have no experience with water cooling. This is my first water cooled rig, which is one of the reasons I decided to buy it rather than assemble it myself as I normally do.
One of the hoses is ambient temp and the other is noticably warmer (though not burning hot - right now at least).
I have a 2 year full warranty from the shop, so they should repair it... I just don't want to be without my baby for as long as it's going to take
Thanks for the super fast answer in any case - I'll see what happens when I return it to shop and update/mark solution afterwards