H80i pump broke?

[*]What CPU and is it overclocked?

I7-9700K no

[*]How quickly does the coolant ramp up and how quickly does it cool down?

The CPU idles around 70C and can hit 100C within a minute at 15% load.

[*]What is the ambient temperature?

24C

[*]Is the cooler intake or exhaust?

I tried both and they seem the same. It's currently intake.

[*]What GPU are you using? (Hint: Fill out your system details fully.)

GTX1660 SUPER

I replaced the thermal paste.

The pump is plugged into my H370N mobo's cpu_fan.

I followed these instructions (admittedly only after I thought the pump had failed, 5 weeks after I made the PC) https://forum.corsair.com/v3/showthread.php?t=168801&t=168801

Pump speed 0 rpm is usually a warning a sign. In this case it is likely accurate since the physical description matches that state. You might get one good run at it from a cold boot, but once you try the coolant and CPU temp will stuck at the elevated level until the liquid around the block naturally cools off. It appears there is zero movement.

Link can still see the pump, so it's either mechanical failure or it can't get enough voltage to start. The post you linked is a reminder to make sure the controlling power header on your motherboard is set to 100%/Full Speed or however your BIOS describes the constant 12v power state. In a pinch, drag all the dots to 100% mark and set it to PWM. That guarantees 12v. If this does not resolve the issue, it's probably mechanical and you need to contact the vendor or Corsair Support to arrange for a replacement.

Thank you for your speedy reply.

In my BIOS, I have "CPU Fan Speed Control" set to "Full Speed".

"CPU Fan Control Mode" can be "Auto", "Voltage", or "PWM". The link said to use voltage, and you've said to try PWM. Neither made the pump rotate.

I bought the H80i from microcenter so I'll return it there tomorrow.

"Full speed" would do it. That is common language for disabled fan control and locks the header at 12v.

That unit needs to go back.