Hi, this is my first time to ask something and i hope i am in the right place?
When I start my PC first thing it makes a slight whirring sound for approx 25 secs then diminishes and disappears, but after playing a game for about 3 hrs the speech seems to break up on my game and then on rare occasions the game will then shut down and I am left with my desktop. I have speedfan and it registers approx 36c after 3 or 4 hours continuous work or playing? Please explain in simple terms, thank you.

Noisy, cold, fan. It is working, but you may want to replace it (or regrease under the sticker on the fan)

Confirm you have the updated audio drivers for your audio card (or motherboard)
Also in some cases it may be just too much cache built up, (after 3hrs!) just run ccleaner on your system regulary

You may want to check Event Viewer" in Control Panel (under Administrative Tools)

Don't know what you got in that box, but the problem could be simple as over heat. I would try blow out all the dust and do a open box test (blow house fan directly into open case) to see if the problem persist. The cpu temp seems ok, but who knows.