The first thing to try would be to update to the latest BIOS version for your motherboard. That will be available on the Intel website download section and as you're new to this sort of thing, the easiest way is to use the Express method and get the file ending in exe. You need to follow the instructions and ensure your antivirus software is turned off during the BIOS upgrade process.
If this doesn't fix the situation, reply back with your full system details incl Power supply details and what model of I3 CPU also the OS you have installed.
I tried the Bios update shortly after the system started to act up. The version I currently have is JGIBX10J.86A.0396.2010.0309.2234
I built the system in March and it started doing this on a very hot day in Aug. Bought the Case, processor and motherboard as a kit.
Mother board DH57DD
Dual boot Windows 7 and Ubuntu
8 gb memory Corsair 2x4gb DDR3 1333 mhz
Apevia X-master BK/500
500 W power Supply
WD HD 1TB
I won't shut down in Windows or Ubuntu. As soon as the system is turned on you can hear the CPU fan running at a higher than normal speed.
In the Bios if I go into Configuration, Fan control, Real time HW monitor and press enter is says you should get temp and fan information and mine shows nothing.
Let me know if you need more info.
Rob - As Flying_Kiwi recommended, you should first update to the latest BIOS (0656) for your board.
And if the latest BIOS makes no difference, the next thing I'd look at would be the Power Supply - the most common part to fail on PCs. I'm not saying this one is faulty for sure but hot conditions (such as caused by hot weather or poor case air curculation) can bring on problems which weren't there previously.
When you do eventually manage to get into the BIOS and look at the voltages, are they all smooth and near what they should be or otherwise? It'd also be worth installing Intel Desktop Utilities and monitoring the voltages there. If you have a spare ATX PSU hanging around, you could swap that in (just for testing purposes) and see what result you get.
Tried to do the BIOS update. If I do the express update the system won't restart properly. I have to hold the power button to get it to shut off. If I try the F7 process it locks up right when I hit enter when it asks if I want to up date the BIOS to the version 656.
I am going to try to get another power supply to try and see if that helps.