Question CPU running hot on Corsair H100i

Sep 27, 2020
16
3
15
0
Hi! Like noted in the title, my i7-9700k at stock clocks is running quite hot on my corsair H100i. My case is corsair's Crystal 280x. I have two intake fans at the front and two exhaust fans beneath the 240 mm rad at the top of the case. I recently realized I had my fans setup incorrectly (the top fans were also intake, so hot hair was coming through the rad back onto the CPU with positive case pressure), so I remounted the water block with new thermal paste and flipped the fans only to see temps change just a degree or two. While Idle, I see temps between 40 - 50 C. While under load, I see temps from 75 - 85 C and sometimes more in certain benchmarks. Ambient temps in my room are ~23 C. I also can confirm that the pump is running correctly with a peak speed of 2400 RPM according to HWMonitor. I don't hear any sounds/signs of trapped air either.
 

Phaaze88

Glorious
Ambassador
-Remove the bottom fans. They're really not doing anything.
-Leave the radiator fans as exhaust.
-Remove the top filter, if you haven't already.
-Run the front fans at max speed.
-What is the gpu?
-Test thermals again.

Physically test that the liquid is moving - you can't always rely on software readings. Feel the cpu block, the tubing and the radiator. It should normally feel warm throughout, perhaps save for the return to block tube.
 
Sep 27, 2020
16
3
15
0
-Remove the bottom fans. They're really not doing anything.
-Leave the radiator fans as exhaust.
-Remove the top filter, if you haven't already.
-Run the front fans at max speed.
-What is the gpu?
-Test thermals again.

Physically test that the liquid is moving - you can't always rely on software readings. Feel the cpu block, the tubing and the radiator. It should normally feel warm throughout, perhaps save for the return to block tube.
Maybe my original post wasn't clear. There are no bottom fans. Just front intake and top exhaust. Radiator fans are currently exhaust. Top filter is removed. I know running the front fans at full speed would definitely help, but I've seen people with both better temps and acoustics than me with the same fans. GPU is Zotac RTX 3080 Trinity. I can confirm that liquid is moving thorough the tubes. I should also note that I already have a cooling curve set in place for my intake fans to throttle all the way up when the CPU reaches the upper 60s in temps. After testing, I'm seeing basically the same results. Idle 40 - 50 C. Then the temps settle around 80 - 90 C under max load.
 

ggrego

Distinguished
Jul 10, 2010
64
1
18,630
0
I would remove the water pump and carefully replace the thermal paste with Arctic Silver and carefully retorque the processor and water pump. Then recheck the temps.
 

Phaaze88

Glorious
Ambassador
Ok. The way you typed it out made me think you had bottom exhaust fans.
I've seen people with both better temps and acoustics than me with the same fans.
But are they running a 3080 in their systems?
That is NOT a cool - no pun - gpu. As top exhaust, the H100i is taking in the bulk of that card's exhaust, so of course that's going to affect the cpu's thermals.
I suggest moving the radiator to the front as PULL intake - do not do push, the fans will be too close to the glass panel.
Try to orient the rad with the tubes entering from the bottom, if possible. If it's not long enough, then don't worry about it for now.
 
Sep 27, 2020
16
3
15
0
Ok. The way you typed it out made me think you had bottom exhaust fans.

But are they running a 3080 in their systems?
That is NOT a cool - no pun - gpu. As top exhaust, the H100i is taking in the bulk of that card's exhaust, so of course that's going to affect the cpu's thermals.
I suggest moving the radiator to the front as PULL intake - do not do push, the fans will be too close to the glass panel.
Try to orient the rad with the tubes entering from the bottom, if possible. If it's not long enough, then don't worry about it for now.
Yeah, I get your point about the 3080, but I should note that at idle, my 3080 is sitting about 15 C (it idles at about 30C and is about 65 - 75 under load) cooler than my CPU and there is no way that the heat from the GPU is heading towards the CPU other than by radiating off of the backplate. The GPU fans suck from under the computer and exhaust out the back. I also unfortunately cannot mount the rad on the front as the GPU is almost the entire length of the case. I had to remove a fan and put it back in just to fit the GPU in. I should also point out that my CPU ran just as hot if not hotter with my RTX 2080 before I upgraded. In fact, my 3080 runs cooler than my 2080 did surprisingly considering the extra 100 Watts it pulls.
 
Sep 27, 2020
16
3
15
0
I would remove the water pump and carefully replace the thermal paste with Arctic Silver and carefully retorque the processor and water pump. Then recheck the temps.
I've just recently done this but instead using Noctua's NT-H1 Paste which is tested to be just as good if not better.
 
Reactions: ggrego

Phaaze88

Glorious
Ambassador
and there is no way that the heat from the GPU is heading towards the CPU other than by radiating off of the backplate. The GPU fans suck from under the computer and exhaust out the back.
~And you're entirely wrong there.
Those AIB models LOVE to dump the majority of their waste heat inside the chassis.
Look at the heatsink's fins. They are guides for airflow.
That warmed air is directed out the sides of the card, after which multiple things happen to it:
-some is absorbed by the motherboard
-some circles back into the gpu fans
-some hits the side panel and rises up... gee, what's up there? Too bad TG side panels are so trendy these days, because glass is an insulator of heat.
-some goes out the back, but the amount that does is such a joke compared to what's going on inside the box

Now, if those fins were oriented front to back, you'd actually be right.

As for the rest:
I should also point out that my CPU ran just as hot if not hotter with my RTX 2080 before I upgraded. In fact, my 3080 runs cooler than my 2080 did surprisingly considering the extra 100 Watts it pulls.
If only it were that simple.
100w is pretty significant. That energy doesn't just disappear - it has to go somewhere.
The 3080 Trinity is just getting rid of it's heat faster than the old 2080 was - that extra 100w of heat still had to go somewhere.

It's starting to sound like the Crystal 280X doesn't allow enough air through the chassis.
 
Sep 27, 2020
16
3
15
0
~And you're entirely wrong there.
Those AIB models LOVE to dump the majority of their waste heat inside the chassis.
Look at the heatsink's fins. They are guides for airflow.
That warmed air is directed out the sides of the card, after which multiple things happen to it:
-some is absorbed by the motherboard
-some circles back into the gpu fans
-some hits the side panel and rises up... gee, what's up there? Too bad TG side panels are so trendy these days, because glass is an insulator of heat.
-some goes out the back, but the amount that does is such a joke compared to what's going on inside the box

Now, if those fins were oriented front to back, you'd actually be right.

As for the rest:

If only it were that simple.
100w is pretty significant. That energy doesn't just disappear - it has to go somewhere.
The 3080 Trinity is just getting rid of it's heat faster than the old 2080 was - that extra 100w of heat still had to go somewhere.

It's starting to sound like the Crystal 280X doesn't allow enough air through the chassis.
Right. I see what you mean by how the GPU distributes the hot air, that will heat up other components, but part of my original point still stands. If my CPU ran hotter with a GPU that got rid of it's heat less effectively (it had essentially the same cooling method as my 3080, triple fan, fins running from side panel to side panel), and now runs a tad cooler with a GPU that expels it's heat into the case, more effectively (I'm going to say the tad bit cooler is a result from applying new thermal paste), then surely my CPU running hot can't be a result of the 3080. Maybe it's the case? After some googling it seems like most other folks are seeing around 70 - 80 C. I'm seeing about 10 more than that on average... seems a bit excessive.
 
Last edited:

Phaaze88

Glorious
Ambassador
@brandonc0431
I asked for some assistance, and got the following so far:
"Faster GPU might be demanding more from the CPU and causing his increases? But everything else mentioned in the thread seems about right.

Might just need better exhaust. Don't see that happening with that chassis.

Maybe slap some 80mm fans at the rear if they fit. Might even make them intakes to give the CPU cooler some fresh air."
 
Reactions: brandonc0431

ASK THE COMMUNITY

TRENDING THREADS