Unexpected high temps with i5 8600k

Tomatoes,

I think 13thmonkey and vMax have pointed you in the right direction, but let's take a closer look at the major variables, and address each of your questions and concerns.

(1) The Hyper 212 Turbo is basically a dual fan push-pull variant of the discontinued 212 Plus, both of which have spaces between the pipes at the base, where the EVO variants do not. The extra fan on the Turbo variant only decreases Core temperatures by about 2°C from the Plus variant, which gives the Turbo similar thermal performance to the EVO. Also, since your Corsair 400C includes just a single 140mm intake fan, installing a second 140mm intake fan would certainly help to minimize case and Core temperatures.

Here's the operating range for Core temperature:

Core temperatures above 85°C are not recommended.

Core temperatures below 80°C are ideal.

Core temperatures increase and decrease with Ambient temperature.

Idle temperatures below 25°C are generally due to Ambient temperatures below 22°C.

(2) The user terms "idle", "load" and "full load" get flung around forums like Gorilla poo in a cage. When left unspecified, these terms could mean almost anything. They often cause confusion and can be misleading. Although load temperatures are much more important than idle temperatures, many users express concerns about high idle temperatures and seek answers.

In order to make a valid apples-to-apples comparison, the same workload and environmental conditions must apply to each hardware platform in the comparison group. So with respect to your questions concerning idle temperatures, if users don't specify CPU utilization and ambient temperature, then we have no perspective.

(3) Is "idle" really idle? Idle means minimum activity or usage. When you were reading "many posts", did anyone bother to mention their "CPU Utilization" in Windows Task Manager? This critical detail is almost always overlooked which causes confusion. Here's what idle should look like:

No apps running, and no on-line activity. No Folding or SETI or "tray-trash" running in the background, and just 1 or 2% CPU Utilization under the "Performance" tab in Windows Task Manager. Under these conditions, an adequately cooled rig with a decent cooler and case running reasonable fan curves, should idle less than 10°C above ambient. A well cooled rig at 1% CPU Utilization may idle as low as 3°C above ambient.

(4) Standard or "normal" ambient (room) temperature is 22°C or 72°F. When you were reading "many posts", did anyone bother to mention their ambient temperature? Ambient temperature is a reference value that Intel uses in their Datasheets for Thermal Specifications. Core temperatures increase and decrease with ambient temperature, so it's a major variable that "many" don't mention. This is another critical detail that's often overlooked, and also causes confusion.

(5) BIOS is not an accurate means for measuring idle temperatures. BIOS runs the processor without power saving features, so you should expect that CPU temperature in BIOS will be higher than in Windows at idle.

A proper method to measure idle temperature is to wait a few minutes after boot up, when Windows completes it's startup processes and services, then settles down into what should be a relatively smooth, minimum idle. Use Task Manager and Core Temp to watch for minimum CPU usage and Core power consumption (Watts).

• Core Temp - http://www.alcpu.com/CoreTemp

Lower CPU usage and Core power yield lower idle temperatures.


A quick Google search found this ... or ... if you just look at the Stickies at the top of the CPUs Forum you can't miss it: Intel CPU Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

CT