>what this small heat sink is cooling?
linear regulator
> And I'm wondering if its supposed to get as hot as it does. Like VERY hot.
Yes. Linear regulators are, to put it simply, just resistors radiating away the input/output difference (dropped voltage). Very inefficient as you can imagine. Whatever the power 3V CPU uses that regulator will eat additional ~50% while being significantly smaller.
> I almost want to put some thermal paste and a tiny fan on it
do you have the urge to mount additional radiators in your car? or modify the thermostat? after all coolant easily hits 100C! 😀
Linear regulators are designed to operate at those temperatures just fine. Dont worry about it.
>One thing I noticed is it bends very easy. So, something to be carful with i'm sure.
yes, dont bend it 😜 Ideally radiator should have its own leg or lie flat on the side. Looking at https://theretroweb.com/motherboards/s/lucky- … r-ls-486e-rev:d Lucky Star went that route in later revision. Of course this would only matter in mobile applications where constant movement has a potential of stressing the part beyond its limits - this is why big capacitors (heavy part on small two legs) tend to be glued down with white snot in power supplies.