Hello, I just installed an EK P240 DIY kit on my de-lidded 3770k. The supremacy evo CPU block was disassembled and I had installed the suggested water jet by the EK manual. The radiator is installed into the side panel with the two Vardar 120mm fans mounted externally pushing air into the case. Everything is leak inspected, bled, and free of kinks or other obvious issues. This isn't my first water cooling setup. At first it was performing great, initial testing at stock clock speed showed around 60c load vs 80c+ with my hyper 212 Evo. After some tuning and overclocking I arrived at 4.6Ghz, 1.308vcore with load temps around 72c max in prime 95. However a few days later, core #1 started loading closer to 90c. I pulled the water block, removed the CPU lid, cleaned both surfaced, lapped the IHS, and reinstalled everything with new thermal paste. Load temps were back down to around 70c(ambient temp varies a lot here) and the difference between the coldest core (#3) to the hottest core (#1) was about 5c. Played some videogames (CSGO) especially on hot days and max load was around 79*c after a few hours of playing and the radiator nicely heat soaked. Come home from work last night after a hot day so room temps are pretty high, ambient temps here vary from 20c in the morning to 35c mid day. Core #1 is peaking at 90c on the desktop running just browser and chat clients! Varying 5~15% load. Ran P95 and MAX temps reported by HWmonitor showed the following: vcore 1.308 core #0 81*C core #1 94*C core #3 78*C core #3 71*C Package 93*C c: I saw as high as 99*C peaks after playing around with some stuff on the desktop and turned off the computer to inspect everything and lower the overclock for now. There are no obvious mechanical issues with the loop. Everything is as it was when I installed it. I tried unplugging the PWM on the water pump to run at full speed and it made no difference on load temps. I woke up this morning and re-ran the test with lower ambient temperature and clocks dropped to 4.5Ghz @ 1.284vcore. core #0 72*C core #1 85*C core #3 71*C core #3 61*C Package 85*C At idle or normal desktop usage, all the cores are at similar temps. The only significant difference is at full load. Anybody have an idea of why core #1 is so much hotter? The rest of the core temps seem to be loading consistently, but #1 seems to peak much higher a few days after re-seating the CPU & thermal paste. The setup. delidded 3770k, after lapping. My goal was to get it flat, not mirror finish. Airflow with the side panel on, should be adequate. TL;DR de-lidded & lapped 3770k on water, one core is abnormally hot after a few days of usage with the other cores loading normally. Temps dropped to normal for a few days after re-seating block and CPU, but now they're back up. Thanks for reading. Also, its good to be back on water. Thanks to HH. edit, I tried running coretemp and it agrees with hwmonitor. I'm reading through information on the sensor test, but it still doesn't make sense why one core is so much hotter than the others. Core movement test has strange results. core #0 29 core #1 45 core #2 36 core #3 32 edit, I re-seated the IHS & water block again and temps are back to normal with max 5*c difference from coolest to hottest core. I guess it is an issue with the mounting. There seems to be a bit of junk in the lines already maybe from the radiator, so I'm going to flush everything out and hopefully shouldn't have any more issues. Still strange to me I've never had this kind of inconsistent issue before.