Weird core i7-4700HQ CPU temp issue (Asus X750JN laptop)

Greetings, NotebookReview peeps -

This is a weird one - really got me scratching my head.

I have a 5 year old Asus X750JN laptop (17"), with a core i7-4700HQ CPU (4C/8T), and it's had a very strange CPU temp from day one.

Under heavy loads (gaming or benchmarking), cores 1,2 and 3 all spike to around 84°C, but core 4 spikes to only around 77°C. In other words, one core of the CPU always runs around 7°C *COOLER* than the other 3, but only when the CPU hits Turbo and goes to 3.4 GHz (all 4 cores show 3.4 GHz).

When Idle, all 4 cores are around 45 - 47°C.

I was under the impression that it's usually one core that runs *hotter* than the other 3.

What gives?

I've re-pasted this CPU twice now, with Arctic Silver 5 (used the thin "line" method on top of the 4700HQ's die), and I also "pre-tinned" the copper heat sink with AS5 (I always clean off the old thermal compound using coffee filter paper and 91% isopropyl alcohol), and I always observe the 4 screw diagonal tightening pattern on the heatsink.

Exact same results, both times. One core is always 6° - 7°C cooler than the other 3, but only during Turbo modes.

Yours At A Loss,

- Trev

 

Maybe warped heatsink, making core 4 having a thicker layer of thermal paste between it and the heatsink. If possible, try to lap your laptop heatsink.

 

Thanks for the reply and the lapping suggestion, senso - I'm now digging into techniques for lapping the heatsink face. Not for the faint of heart, but worth a shot.

Thanks again!