Computer crashing while under load

   I'm currently running an AMD FX-4100 with the stock cooler, and a Sapphire Dual-X 7850, both stock clocks.  I do have 1 120mm fan at the back of my system, exhausting air, but no fans other than that.  So what's the problem?  Should I get another 120mm fan for intake?  Or buy a Cooler Master Hyper 212 Evo?  Do I just need to go in and clean off some dust?  Also, could I be harming my computer by using it?  I'm trying to not put as much load on it, but it will still crash if I accidentally push it too hard.  I know that last time I had an issue like this, my CPU practically melted onto it's cooler, however that was an all out fan failure, and that was on a Pentium 4.

     I'm not usually this bad with computers, but I'm sure some people here know a lot more than me about cooling.  Thanks!

(I did NOT choose these parts)

CPU: AMD FX-4100 @ 3.6GHz

CPU Cooler: stock

MOBO: GIGABYTE GA-970A-DS3

RAM: Kingston HyperX Blue 2X8GB DDR3 @ 1600MHz

Video Card: Sapphire Dual-X Radeon HD 7850

Power Supply: Cooler Master EX2 Extreme 625W

Hard Drive: WD Blue 1TB (40GB free)

Case: Cooler Master Elite 335U

 

Firstly, list your pc specs (including the power supply), then tell us how long you had this pc before this problem occur. When did you last open the case to clean it?

Updated.  I've owned the computer for a little more than a year now, and had some dust problems with the graphics card in the past,  however I wasn't actually the one to fix it, as this is a shared computer.  But everyone else who uses the computer uses it either for the same type of gaming as me, or stuff much less intense.  I've opened the case in the past month, however I was just really looking at the system, not cleaning it.  I can't really remember the last time it was cleaned, actually, however it doesn't look like a crazy amount of dust to me, so somebody else might have cleaned it recently.

In theory the build looks fine. Although the power supply doesn't have 80 + efficiency, it should be ok for now. But it could be the culprit. You could go buy a better psu to see if that was the problem else its still a recommend upgrade for the PSU anyway.

Do you know the temperature of your cpu when turning it on? Perhaps the thermal paste has dried up. 

Boot into a Linux OS, if you're not already running it, install a few CPU-heavy apps or games and see how it holds up, this way you can be sure it's not just a problem with Windows. If this doesn't work or for some reason you can't boot into Linux, I would run your install of Windows in safe mode and load the CPU to max with a benchmark application, if your system still crashes I would say it's a problem with your hardware, in which case the PSU upgrade suggested above might solve your problem.

I would say to put a fan for intake, It would allow more airflow which might be your problem. Other than that, it might be your hardware is not getting enough power. Check to make sure everything is plugged in.

EDIT: my system crashed due to not having the cpu fan plugged in (I forgot that I unplugged it) However it crashed before the OS booted up, so that is most likely not your problem.

EDITV2:

But the Cooler Master is cheaply build, and becomes a bit unstable when pushed over 500W

From Eric_M's review on http://us.ncix.com/products/?mode=productreviewread&product_id=71920

Heat is the most common cause of crash after a bit of time under higher load levels.

If it was stable for a year in its current configuration, then adding an intake will do little to resolve the issue since the case certainly isn't air-tight.

 

Heat - if you brought it to a professional - heat would be their first instinctive answer. And, generally speaking here the "Audience" has replied with the same thing. More air, better air flow - does improve things; but moreso in an environment that is already functional. You have a dysfunctional system, so you need to find the cause before you can simply "add more stuff to make it work better".

That said: Heat isn't the only cause - just the most common. Start by going to download aida64. Once installed - a trial version is fine - go to Tools, System Stability test - Check the option to stress CPU and hit start. you will see your CPU temp climb. The CPU will throttle itself if it gets too hot, and crash if it detects it is overheating. All of this is done very quickly because the cpu wants to save itself.

Since you didn't do the build you don't know whether your motherboard BIOS has been configured to ignore cpu temperatures. If it has, that is quite a noob move and you should shoot whoever built it for you. So, if your temp climbs to 90-100degrees, and the system doesn't shut down - stop the test and don't let it run above 90-100degrees for any length of time.

If it gets that hot - then clean the heatsink and apply new thermal paste.

 

If it were mine - it would be done outside of the case (mobo removed) so as to get an excellent working area.

Doing it inside the case is fine. Remove your cooler, clean the CPU with a decent piece of cloth that doesn't have frays or doesn't leave excessive fuzz behind. Wipe it a few times - alcohol isn't necessary, just a few wipes.

While the CPU heatsink is off, vacuum it out, and use a blower to blow out the metal fins.

 

Youtube: Clean cpu and heatsink. You'll find tonnes.

I would add that before doing stress tests etc you back-up your data and do a full system image (unless you want to spend four days downloading installing updates and rebooting and reinstalling software [half of which you have lost the keys/media for]).

   If as jalotway suggests the system has been stable for a year then it is unlikely to be the actual setup, look elsewhere for the source.   Heat is the first thing that springs to mind on uncommanded shut downs after a while.  Try a thoroughly good clean (I have even seen leaf blowers advised )

http://www.youtube.com/watch?v=l0ohF6zthOQ&list=PLEA5C9209A487A062&feature=c4-overview-vl

if that does no good then try the replacing power supply thing.

I would see if you have easytune installed and if it is installed i would uninstall it as i have had issues with it in the past with it.

If that is not installed i would just try and get a new cpu cooler and at the same time clean out the case.

If that still doesn't work i would try and look at getting a new psu, the one you have now isn't the best of quality and might be causing the crashes.