It definitely could as if, for example, the CPU starts to overheat it will "throttle back" to avoid self destruction by overheating, BIOS settings can also force a shut down if certain temperatures are exceeded, the other items can have similar built in protection.
its the pentium 775 socket fan, sometimes when the pc crashes i have to clear the cmos to start. if i can't fix it i have to take back to novatech in portsmouth, [also had problems with ram sticks going defective] at present my remaining sole ram stick is ok. As i type the fan is chugging along like an old steam train labouring along. I have the side of the case off and the case it its side which seems to prevent some of the crashing but the fan is as described still.
Sounds like a defective heatsink fan but if the system is only three months old and has already exhibited all those problems you have listed I would demand a replacement.
It is possible that some thermal damage has already been caused to the CPU or other components, I would also avoid using the system if possible, as you have the side of the case off do you have a desktop fan that you could place beside the case and direct the air flow into it?
can you take the fan out and connect it to a 12v battery ? if it runs ok for the amount of time you have it connected then its not the fan !,, how many fans have you got in total in the chasis ? what processor have you got inside? what speed RAM >? xx
The fan runs from the same 12V supply as the drives. If the PSU was the cause then the hard drive would be in trouble and the computer wouldn't work. The most likely cause is a faulty fan, but if the fan is temperature controlled then it could be the controller that is at fault and that may be integral with the motherboard. As the system is only 3 months old you are likely to invalidate the warranty if you start tinkering.