Since most GPUs can cool themselves, it's likely that GPU cooler is designed to be an
additional measure for keeping a GPU cool - which means it may lack the RPM to effectively cool a CPU (to prevent unnecessary noise, it will likely be slower than a CPU fan if it's an additional measure rather than the only cooling mechanism). It does not state the speed, however, which makes it very difficult to tell.
EDIT: Also, I'm generally confused by your situation. You didn't fit a heatsink to the CPU to begin with? As in, you left it completely bare?

And how come you didn't have a heatsink and fan lined up ahead of time? They're pretty critical components
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