High CPU temps with my WC?

Hello.
Few days ago I built my first WC system.
Res. Ek 140 d5 res-pump combo
Pump. D5 MCP 655-b
Cpu block. Ek supreme HF
Rad. EK 280 rad (its around 50mm thick, i dont remember and im at work right now).
Cpu. Pentium G3258

I dont know if its because of wrong thermal paste aplication (ic diamond line method) or something with my loop. I oced it to 4,9 ghz with 1.425 vcore, vcache 1.3 and vccin 1.93. It sits on maximus vii Hero. I get temps to 84°C. What im really worried about are core temps . one is max 84 and second one 74, isnt 10 deg in temps really wrong? My rad is sooooo cold (like with pc turned off). Should i reapply thermal paste? Maybe something like silver 5? What is safe voltage for this cpu? Isnt 1,425 too high?
Thanks for help

Sounds to me like a bad block mount. I would remount the block. Also I would check the amount of thermal paste. Too much will act as insulation as too little will not ensure a good contact.

What Program are you using for Load testing? Linpack or Prime with that much Vcore will push the temps up but not that high with a pentium. I agree it most likely is a bad mount of the WB. Rice Grain method for the TIM.

I would check the tubing and see how warm it is and where its warm most since the rad feels cool to the touch. My instincts say it might have to do with the flow. Make sure that pump is pumping first and foremost and at what speed. I'd than take a look at the mounting.

I am not a OCing guru but I've read in most cases to only go past 1.4v for benchmarking. As for 24/7 use, 1.4v is the max I'd recommend.

Actually bigger than a rice grain. Maybe two rice grains or slightly smaller than a pea. I use about a pea size, but a 2011 CPU is a lot larger.