Regular Crashing, Why? (win10)

Hi, apologies in advance for the vagueness of this post. Hoping someone can help me.

I've been using my PC (made it myself) for around a year with no issues - used primarily as a media server/player for music.

Recently (over the last week or two) it has started crashing. Things seem fine on startup, and the crash always seems to occur around 30 mins in to using the machine.

In terms of the crash itself, the machine just seems to "freeze". I don't get any error message and the screen looks the same. I can still move the mouse cursor but am not able to click on anything. Alt/ctrl/del does nothing at all. If I power off the machine and start up again, it works - though it will crash again after 30 minutes or so. It's happened again just now - I'm on my desktop, and the cursor is a spinning blue circle. I've tried leaving it for ages (in case it resolves spontaneously) though it never does.

In terms of the cause, I don't know. The only thing I have done differently recently is use the machine for some emulation (using Hyperspin and the MAME emulator). I can't quite remember if I installed anything in particular during this time or updated any drivers - I don't think so, but can't be sure.

I appreciate that this doesn't give much to go on, but could really do with some help or even some pointers in how to start investigating.

PC specs: Asus Z97 Gryphon mobo, Intel i7 4770T CPU, 8GB DDR3 Crucial RAM, Sasmsung 850 SSD.

Many thanks

 

Is there any dust/debris interfering with ventilation? What are the temperatures like?

 

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