It's actually the GPU fan. The smaller chip with the tiny heatsink is the CPU, oddly enough.
Unfortunately "ARX Cera Dyna VGA COOLER" is just a generic sticker and doesn't actually tell us what model of fan it really is - dozens of completely unrelated ARX-branded fans all have the same sticker. If the fan is dying (buzzing/growling/barely moving and doesn't have a lubrication hole hiding underneath the sticker) and you can't find an OEM replacement, just look for a cheap faulty/dead MK6 video board, they have the same fans (of course, ask whether the fan itself is working and wasn't actually the cause of the video board dying!)
If it's moving ridiculously fast like it's getting the full 12V, is the fan/heatsink sitting straight and not loose? I don't know if they're like a PC fan where they spin faster if something is getting too hot (I nearly cooked a 3 GHz Prescott P4 like that once, the heatsink was partially resting on the edge of the CPU socket, resulting in the jet engine noise followed by loud PC speaker beeps, an automatic power-off shutdown, a 93°C CPU temperature in the BIOS after I rebooted it, and the sound of a four letter word echoing throughout the house and me quickly ripping the AC cable straight out of the power supply).
That said, I wouldn't be surprised if any similarly-sized video card fan could be modded to fit*, underneath the fan and heatsink is a lowly VideoLogic Neon 250 chip (aka PowerVR Series 2), which was originally a PC video card from late last century. Note that it is a 3-pin fan however, and the machine will complain and shut down if it can't detect it and/or if it thinks it's spinning too slowly.
*I am not in any way responsible for blowing up your MK6 board. Always make sure the voltages, current draw, wiring pinout, fan speeds and airflow are the same between fans.