i7-4790K core temps vary markedly

[Engr62]

I've got a small form factor PC that I travel with that has an i7-4790K CPU (at stock speed). It's being cooled by a Big Shuriken 2 Rev. B air cooler. When run at 100% load, the CPU has peak core temperatures of 82C (core 1), 74C (core 2), 70C (core 3), and 66C (core 4) with the steady-state values just below these temperatures--for instance, core 1 will bounce between 79C and 82C. These are the temperatures reported by HWMonitor and CAM. CAM also reports the average, which is usually around 77C.

I've tried remounting the Big Shuriken as well as other coolers on this CPU (Noctua NH-D9L, Raijintek Pallas, Cryorig C7, and Cryorig M9i both in cases and on open bench set ups) and still get this behavior--where there is quite a bit of difference in the core temperatures.

I've tried running Voffset of -0.025, -0.050, etc., and it's only stable at -0.025 V (not much difference on peak temperatures). If I disable turbo in the BIOS, I can keep the peak temperature below 80C, but still have the significant difference in core temps.

My i7-8700K doesn't exhibit this behavior... with differences in peak core temperatures less than 5C.

I'm sure that the CPU could really benefit from a delid, but I haven't gotten the nerve to do it yet. Will one core running above 80C shorten the CPU's life, or is the average more indicative of lifespan?

 

[VanGoghComplex]

Can't speak to the longevity of the thing, but I've done and redone delids - the paste between the IHS and die definitely contributes to the variance core to core. The goop on a stock 4790K is probably old enough to start showing some age-based degradation.

Also can't tell you if a delid is really necessary in your case, but I can say that it's a lot less nerve-wracking than it sounds. There are a number of tools on the market that make it really easy to do ( I'm a big fan of the Rockit88 tool ) and there are some real gains to be had by changing to a liquid metal TIM like CoolLabs Liquid Ultra.

 

[horrorshow]

I prefer to keep the CPU under 75c no matter what.

Def look into delidding. It's time.

 

[Engr62]

Thanks for the replies.

Also can't tell you if a delid is really necessary in your case, but I can say that it's a lot less nerve-wracking than it sounds. There are a number of tools on the market that make it really easy to do ( I'm a big fan of the Rockit88 tool ) and there are some real gains to be had by changing to a liquid metal TIM like CoolLabs Liquid Ultra.

I'm not as afraid of damage during delidding as I am just not getting the IHS glued back in place so it doesn't look like such a hack job. I've seen some pretty messy silicone glue applications. If I do delid, I'll probably just use a TIM similar to the original. I've seen some of the videos with the underside of the IHS darkened due to the reaction of the liquid metal with the copper IHS. Plus, some say you need to reapply the liquid metal from time-to-time, while others argue that you don't.

I prefer to keep the CPU under 75c no matter what.

Def look into delidding. It's time.

I'm with you there. I prefer to keep my CPUs under the mid 70's (or better yet under 70) as much as possible. You are probably right. It's either time to delid or underclock.