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Question Sudden Cpu Temp Spike (90c idle)

Nov 19, 2019
Hello, something very strange happened to my computer today. I was using it, and it was doing perfectly fine, but then all of a sudden my fans went into overdrive. Restarting my computer and going into the bios relevealed that my cpu was now suddenly idling at 90 DEGREES CELSIUS.

My cooler is the corsair h100i v2, cpu is an 8700k, and from what I can feel, there is still vibrations/movement in the tubes. I have also tried replacing the thermal paste (a desperate attempt to fix the issue). I'm stumped.

The way the temperature was rising on the cpu, as shown on the bios makes me fairly confident that it's not a sensor issue for the cpu, but some problem with the cooler. I also felt no heat from the pipes, but I'm not sure if you can usually feel heat radiating from the pipes in the first place.

All the other temps on my rig were normal. Any explanation, insight, and tips to try to get my pc back into running shape without dishing out some bucks on a new cooler would be great, and I appreciate any help on this issue.



First off, list your specs like so:

Including the version of your OS. Then look into the version for your BIOS and see if you have any updates pending. You will need a replacement cooler just to see if the AIO has given up the ghost.

FYI, in order to troubleshoot and identify a culprit you will need a controlled environment which will mean you having a spare component to verify that the original is faulty/failing.


... fans went into overdrive ... bios ... 90 DEGREES CELSIUS ... corsair h100i v2 ... 8700k ... vibrations/movement in the tubes ... felt no heat from the pipes ... get my pc back into running shape without dishing out some bucks on a new cooler ...

On behalf of Tom's Moderator Team, welcome aboard!

Regardless of feeling "vibrations", it's highly likely that bio-contaminants and particles from galvanic corrosion are constricting or completely stopping coolant flow.

Fortunately, Corsair has a five year warranty, which much to their credit, they honor without difficulty. I suggest that you submit an RMA request for a warranty replacement cooler. In the interim, as my esteemed colleague, Lutfij has suggested, any spare backup air cooler should bring your idle temperature down to a reasonable level and make your rig at least usable under light to moderate loads, as well as prove that your H100i v2 has indeed failed.

Although you haven't mention the age of your AIO, if we assume it was purchased new with your 8700K, then it's perhaps about 2 years old. Flow problems due to blockages are typical for AIO's. Many AIO's are known to fail within a 2 year time frame, and never survive to reach, let alone exceed their warranty period.

Apart from the potential for a coolant leak, there are several problems common to AIO's. Here's some information you should know about AIO's, but with respect to troubleshooting, pay particular attention to the double red bullets below:

• All AIO's will eventually fail. It’s not a question of if; it’s a question of when. Pumps can have component failures in the stator electronics that drive the impeller, which is a moving part that can wear, so those which run 24/7/365 are prone to premature failure. AIO units are notorious for failures due to inferior pump quality, whereas custom loops typically use high-end pumps which have greater longevity.

• Coolant can slowly evaporate over time due to "permeation". However unlikely it may seem, coolant can actually dissipate directly through the tubes. This can introduce bubbles into the impeller chamber causing "cavitation", whereby coolant flow is impeded or interrupted.

• AIO's are sealed Closed Loop Coolers (CLC), which unlike custom loops, are not designed to be disassembled for the water block and impeller to be flushed, cleaned of bio-contaminants and radiator sediments, then refilled. Bio-contaminants gradually accumulate over time and will eventually clog the water block and radiator, thereby reducing flow and thermal efficiency. This is evidenced by Core temperatures that slowly increase by several degrees over periods of several months to a few years.

• Also unlike custom loops, AIO's use dissimilar metals (aluminum radiator / copper water block). This causes galvanic corrosion which produces sediments that accumulate over time, resulting in blockages and flow problems. Even new AIO's may contain radiator sediments due to inadequate flushing after manufacturing. Experienced builders of custom loops will always thoroughly flush brand-new radiators. Flux, solder and metal fragments are typically found in the flush water when it's poured through a strainer.

• • For no apparent reason ... OR ... by simply installing, moving, tipping, handling or otherwise disturbing a NEW OR OLD unit, particles can become dislodged, whereupon the next power-up, the now free-floating particles can circulate into the impeller chamber and constrict or completely stop coolant flow. Since the impeller is magnetically coupled to the stator (no direct shaft), the unit may "appear" that it's running while no actual flow is present. "Hearing" the unit running or "feeling" vibration can be deceiving as it does not necessarily indicate flow, nor does Pump RPM in BIOS or various software utilities. Moreover, as fan vibration can "telegraph" throughout the entire AIO unit, it's often mistaken for pump vibration.

• Without an actual in-line sensor, proper flow is difficult to confirm. Under normal operation, even with the CPU at 100% workload, there should be only a minimal temperature differential between the tubes. However, if one tube is hot while the other is cool, or the water block is hot while the radiator is cool, it indicates little to no flow. Surface temperatures can be verified with an infrared (IR) thermometer.

Sorry for your difficulties, but an RMA replacement will solve the problem. Once again, welcome aboard!

CT :sol:


Dec 9, 2017
When you get your replacement, make sure that you power the cooler correctly. These coolers get all of their power from the CPU_FAN header. What the manual neglects to tell you is that you need to set this header to full speed/100% power at all times. Not doing often results in an early death for the cooler.
Corsair will honor the warranty - it is, after all, their fault for neglecting to mention such an important little tidbit in the manual.
Check out the Corsair AIO FAQ at http://forum.corsair.com/v3/showthread.php?t=174442 - this is discussed there.