H115i and I7 7700k : heat spikes

Hello,

 

I recently built a new PC, with a I7 7700k and using the H115i cooler. I've already built 3 PCs but never with water coolers, but the principle is the same ^^.

 

My problem is that my I7 7700k is having heat spikes, like random +10 to 30°C spikes even with nothing special running (with 2% load). This caused the fan to go max speed for 2sec and then back to normal multiples per minute. I "fixed" that by setting a custom fan curve based on the water temp, but i'm not a huge fan of that since there will be a delay before water heats up.

 

CPU package temp show around 45°C on idle (without counting spikes and with both radiator fans going ~1300rmp), and water temp is 30°C (with room temp of 27°C). Also I hear no sound diff between the silent and perf setting for the pump.

 

I followed the manual for install, everything went well, placed the backplate, the the screws into the MB and through the backplate. The screws were not going fully through, the back plate could still be pulled back a bit (I guess thatis normal since the screws are not supposed to press against the MB). I placed the pump and the thumbscrews,by screwing them well. The pump doesn't seem to move if I try to do so

 

Is that possible that the pump is not well placed or something? How to see if the heatsink is touching the CPU (with enough pressure)? Do you maybe need to apply your own thermal paste? (would be stupid since it's pre-applied and for a product in that price range you would expect the paste to be good enough)

 

I'm really worried about that, I haven't done stress tests or anything for the moment. If you tell me this is normal, I'll deal with it but I don't want to damage the CPU nor the cooler.

 

Thanks.

I "fixed" that by setting a custom fan curve based on the water temp, but i'm not a huge fan of that since there will be a delay before water heats up.

 

This is how the cooler was supposed to be set up from the start. The included fan curves (Quiet, Balanced, Perf.) are based on that value as well. The fans have no direct cooling effect on the CPU. It's heat is generated as a result of voltage and the IHS and cold plate conduct that heat away (to an extent). That is the only way any cooler can work. This is also true of any air tower. Heat is conducted away and the fans try to move it somewhere else. The advantage of a water cooling system is you have a bunch of water to carry and hold the heat energy. In effect, you have a holding tank. With an air cooler, it's whatever you can hold in those little pipes before the heat starts building up back to CPU plate, usually a few seconds. With a water system, you can go much, much longer and fans do not need to respond to CPU activity. The more water you have, the more you can absorb at one time. Your average CPU temp with go up 1C for every 1C increase in coolant temperature (H115i Temp). That is why the fan speed is based on that value.

 

As for the spikiness, welcome to Kaby Lake. Google that phrase or look on any one of many posts in this forum with the word 7700K. You can tame the voltage swings down through BIOS settings, but it is motherboard specific to some extent. Take a look at some of that material and see if you can calm it down. The backplate is supposed to be loose when putting together, then tighten up when everything is finished. If it was loose or not making proper contact, you would see more the spikes at idle and the first time you put any serious load on the CPU, the temps who sail into the thermal thottle zone. I suspect you put together correctly, but that can be examined further. We can only interpret based on data with no physical access and that makes it a bit tedious. The odds are you are experiencing the same doubts as other Kaby owners when firing it up on the Auto settings.

Ahhh, the 7700K.

The TIM is horrid and the voltage changes are dramatic. It's a poorly designed chip.

 

I was able to get my 7700K to stick to slightly less-bad temperatures by delidding it and applying a proper metal interface before relidding it, but the darn thing jumps around like mad. Expect that. As long as you don't see it exceed 95C, it's staying below Intel's 100C TJMax and they're perfectly fine with that. Extra thermal change simply means you'll have to buy a new chip from them sooner they figure.

 

Unless you intend to delid the CPU, as long as you don't see temps hit 100, it's "Working As Intended"

OK thank you guys! ;)

You can still take some intermediate steps to settle it down by setting a specific adaptive or fixed voltage in the BIOS. The auto voltage setting is always deliberately high to accommodate all CPUs, bu these last two Lakes are very elastic when under load. It will keep taking voltage when under stress. The exact mechanic and manner of setting it varies a bit from brand to brand and that is the motherboard specific part. Sometimes a negative offset on adaptive can be more trouble than it's worth. A fixed voltage with C-states enabled is likely a quick fix, but you'll need to figure out how much lower you can go. Some 7700K's bin at more than 0.20v over what's necessary for the stock frequency.