H50 installed, 90c idle temp

I just installed an H50 closed loop cooler into a new build, it had plenty of good enough reviews to try. I took my time on the install and feel good about the thermal paste amount, tightness of waterblock, and the general install. I have the radiator's fan hooked into "opt_cpu" on the mobo, as the install manual recommended, and hooked the pump 3 pin into a direct molex-to-3-pin 12V coming off the power supply to give it continuous, unthrottled power. I booted the pc and after checking the cpu temp in the bios, it is getting up to 90c at idle... I shut it off and only have it on for brief testing periods after noticing this. I tried plugging the pump power into the "cpu_fan" header on the motherboard to test the power to it, and it is behaving the same, same temp rises. I've felt the tubing and pump and can't really tell if it's operating or not; there's a vibration to it but it may be the case fans. The radiator does not seem to warm at all during use, either. Maybe it's on but not pumping fluid? I cannot tell what is going on here. Any experience with this or advice? Thanks.

Check the pump RPM of the cooler via the BIOS. If it's connected to CPU_FAN, the reading will be under CPU Fan/RPM.