Random shut down

[chinadollpr]

MY IMAC RANDOMLY SHUTS DOWN AND WELL YOU TURN IT ON AND STARTS UP NORMALLY CAN ANYONE FIGURE OUT WHY. HERES THE INFO TO MY IMACiMac
Model Identifier: iMac12,1
Processor Name: Intel Core i5
Processor Speed: 2.5 GHz
Number of Processors: 1
Total Number of Cores: 4
L2 Cache (per Core): 256 KB
L3 Cache: 6 MB
Memory: 4 GB
Boot ROM Version: IM121.0047.B1E
SMC Version (system): 1.71f22
Serial Number (system): D25HF34SDHJF
Hardware UUID: 15023722-E054-501E-8883-460759328221

 

[Failurbydesign]

Run a memory test to see if you have bad sticks. I just had this issues and after a handful of reboots my drive wouldn't boot. Free some time and a new install I ran some tests ad found the sticks had failed.

Google memtest it installs ad you can run the commands through terminal

 

[macthefork]

You can also check your Console Logs (in Applications > Utilities > Console app). This should show what is occurring when the iMac shuts down. Make sure in the left hand column it's set to show All Messages.