PC shutdown when playing Battlefield3

Your PSU also has heat related issues. Clean you PSU.

To try:
1) Try gaming with each graphics card separately (physically remove one).

2) run MEMTEST

I suspect it's a failing graphics card or motherboard. I see no heat issues here.

PC Check is very good software for testing a system it's a shame about the price, I bought this for my business.

http://www.eurosoft-uk.com/virtualpccheck.html

never seen anything better.

It seems like the dust was weighing too heavily onthe fins of the fans and making them spin slower. You might want to consider actually removing your fans and wiping them clean, any excess dust or grime can make the fans less balanced and may still cause them to slow down or work improperly.

Take a snapshot of the inside of the case so we can see whether you have actually removed the dust from the PC.. it's not hat we don't trust you but even a slight accumulation on the circuitry of the motherboard could cause heat issue.

PC Cooling:

Do you have both a FRONT case fan sucking air in as well as another TOP case fan sucking air out?

That's in addition to the Power Supply fan and CPU fan.

I think you got too many fans scking in air, it's not cool air either, it is quite warm and could be affecting the airflow from within (maybe). You really only need one fan sucking in air and only if your case is practically air tight. Dust can impact on the fins of a fan making it spin slower and unevenly especially ball-bearing fans.

The ram is perhaps 3 x 2gb @ 1066mhz, it's an unusual speed that is rarely acquired but not saying that is isn't compatible, it just might be slowing the cpu or in some way affecting the performance, you might need to up the ram to 1333mhz or 1600mhz. You should refer to the QVL before acquiring better ram, there is info in there that will be helpful in you choices. Apparently, XMP ram ram can only be used with one stick per bank.

CPU - Core i7 920(2.66G,L2:4x256KB,L3:8M, rev.D0,130W) it's only 2.66ghz, a rather slow performing CPU.
The CPu and the ram are both slow performance hardware, it mght be that they are not good enough for Battlefield 3 or atleast, high FPs for any long period of time

Most gamers would agree that an i5 would have suited you better than an i7 which is more suited to programs rather than high fps PC games. The video card is a high performance card that might be affected by the low performance cpu and ram. Also, 6gb is not much, you would be better with 3 x 4gb (@1333mhz).

I noticed that the motherboard (on the manufacturer site) has the second set of 4 of the 8 pin connectors for the 12 volt support power, covered by a plastic lid, if you haven't connectedt he 8-pin connector the that connection, that could severly impact on the performance of your motherboard aand may very well be the cause of your issues.
http://www.asus.com.au/Motherboards/Intel_Socket_1366/P6T_SE/#specifications

So, even after all that, it could be that you won't be able to play PC games at high FPS for more than a few hours without issues occuring.

I think your current temps are fine, you should consider an exhaust fan nearer to the gpu, though. Many Graphic cards do have temps as high as 75C, they just work better at higher temps. The overall temps seem good enough although they would be better at slightly less.

I'm not sure about your case, the newer models have the PSU seated at the bottom of the case whereas older models had the PSU at the top of an upright desktop case. Being at te top, a PSU with a side fan would be blowing over an open area but the bottom fitted ones would be blowing air closer to hardware and be possibly suffocatig the video card, and sound card and any other card fitted in the PCI (e) slots. Take your snapshots (it's a pain having to do so) and then we can see whether you have adequate air flow, ventilation, and circulation.

Computers are supposed to operate at a certain and differing temp, they all use electricity which is not something that is ever cold anyway. :/

I don't think the ram can be overclocked safely unless the ram is specified as OC.

About 5 years ago, the plastic cover on the other 4pin 12 v connector, I had that on mine, I had no idea is was actually covering anything, my PC guy actually warned me about it, so I always check for it now. The extra power is for the gpu and the cpu. I didn't have any issues prior to then, but I wasn't playing games just using Office apps.

That ram is only a kit of 2, you'd need a kit of 3 so you got a single ram and a pair, for 3 x 2gb.
Also, the ram is 2.2v, you should only use 1.5v, you can't overclock the ram, it is already way too much over the clock ratio for your motherboard.
Your issues are related to your ram being too high in volts, you might not notice the difference until you do something that requires extra performance (and power). You might notice pausing or occasionally freezing of the screen. It's like there is miscommunication between the ram and the cpu and the video card for a brief moment.

Edit - Hang on, that's not your ram, the one in the link is DDR2, you got DDR3 ram.
The "experts" say that you only need a pair of ram in triple dimm slots but I'd rather use the preferred triple kit of ram, for best compatibility.

Speedfan:
I never liked this program because many of the settings/results were incorrect. I'm not saying yours are.
*If the above settings are correct then the temperatures seem normal and fine to me.

RAM:
First of all, I see little point in recommending 12GB over 6GB for gaming. There are plenty of tests that show 8GB can have a benefit over 4GB (not all, just some) but going above 6GB is unlikely to provide much, if any gaming benefit. While it's certainly possible to use more than 6GB if you have it, there aren't many scenarios where having more than 6GB actually benefits game play as Windows would remove any non-gaming applications from RAM if it needed to.

Triple-Channel:
Most motherboards support dual-channel but yours is triple-channel. So it appears your RAM is installed correctly.

RAM SPEED:
You are likely slightly bottlenecked with 1066MHz DDR3, however that varies by the game, CPU and other settings. It's difficult to determine how much difference this makes. There's rarely any point going above 1600MHz.

Overclock the RAM?
No.
You purchased 1066MHz DDR3 and are running at that speed so don't overclock it. If you think faster RAM would benefit then BUY a new triple-channel kit and SELL your old one if possible.

IF BUYING:
I believe the (OC) in the motherboard part means if you overclock the CPU. For example, if you stick in a 1600MHz kit you need to overclock the CPU above 1333MHz (1600/1333 = .2) by 20% otherwise your "1600MHz" DDR3 clocks at 1333MHz. I've heard reports it doesn't always work the way they say, however that shouldn't affect what you purchase. You'll just have to experiment once you buy it.

So, if buying I recommend Triple-Channel, 6GB (3x2GB), 1600MHz memory (I like G. Skill) such as:
http://us.ncix.com/products/?sku=34719&vpn=F3-12800CL9T-6GBNQ&manufacture=G.Skill

RAM setup:
1) ensure BIOS is up to date
2) choose "XMP" if possible to auto-apply settings
3) If 1600MHz at proper timings are set you're good (again, I'm not sure if you would get 1333Mz or 1600MHz with stock CPU settings)

*I suggest you run MEMTEST and your games for a day or two using STOCK CPU and memory settings. Then, if you wan to overclock the CPU that's fine but you need to ensure to not overclock beyond the RAM's frequency. The CPU and RAM often share a Base Clock so that increasing the CPU base clock also increase the RAM base clock.

Not too confusing I hope...

(If I've made a mistake, please NICELY correct me. I'm getting frustrated with the rudeness by some people in these Forums. Cheers.)

Hey, thanks for the pictures, it is a bother having to do them, I'm glad I only answer Quesations and not have to provide images..hehehe.

You've got 4 hdd's, 2 video cards, the PSU is bottom-based, and there si no extra space for air circulaiton. Basically, you got all that stuff crammed in like a shoebox.

The PSu top fan is blowing directly at the second video card that could impact on performance of the second video card. I think you need to get a full tower case. Having the side off the case does impact on how the fans behave for the cpu etc, they turn at slower ratios than when the side is in place but because when the side panel is fitteedm, there isn't enough space left for air to flow freely around the case. The PC cases that I use are 19cm wide, they allow for extra fans above the video cards, your case seems to be only about 12cm wide.

The first gpu could have been getting hot because you had left off the 12v connector to the motherboard, the other spare connector but. even so, there is not much space for ventilation or air flow. You don't have to crossfire (bridge) the video cards to get extra performance from the second video card, just having it seated in one of the PCIe slots gives the first video card extra video ram.

You can't monitor internal fans if they are connected via molex cables, you need to acquire proper fans that connect to the motherboard (fan1, fan2, etc).

On closer inspection, your PC case looks like a flat top design, it sits horizontally to the desk and is not really an upright desktop case, is that right? There seems to be a ventilation section in the "base" near the PSU.

What's that thing with the two blue circling "eyes", is that a cooler for the ram?

Overall, the Pc case looks too crammed, to allow proper air flow.

The Pc cases that I use, you can no longer buy retail, you'd only get them from Pc recylcer places or off the street (dumped). I'm not sure you can even buy a full tower with adequate width anymore, they all seem to be slim and trim.

Fans that connect directly to the motherboard - they use either a 2-pin connector or 3 pin connector plug. The motherboard (bios) then monitors the rpm of the fan. It can be a good way to measure whether your PSU is providing adequate power to the fans.
http://www.frozencpu.com/cat/l1/g36/Fans.html

THat's a good idea to keep you spare hdd's in the case however it does increase the overall weight of the PC (to about a ton!).

I'm not sure that ram coolers are such a good idea, ram works better when they are hot, they are not supposed to be cool at any time but. as you say, they don't seem to impact greatly on the ram and more likely cools the motherboard however, I think they are superfluous and should be removed to allow more air flow around the motherboard, you might want to start a new thread under CPU Category and ask about that, though.

If the PSU has the side fan facing the side of the case then your PC case is a flat top and not an upright desktop case which mean it must be sitting horizontally for the PSU side fan to exhaust any air otherwise, the desk would impede the performance of the PSU, causing it to get hot and could be the cause of the sudden shutdown.

You would be best to place "bricks" at either end of the desktop case so as to lift the case up away from the desk so as to allow more breathability under the case itself. Although I though it was a flat top case, it really isn't though, it's a tower but the underside vents are being blocked by the desk itself.


The Radeon 7850 would probably not be any better because of your slower cpu and ram speeds.

Disclaimer:
Sorry, I'm not really an expert, I just try to point out the things that might intervene in the running of a system but my advice is purely conjectural and you should use your own judgement as to what really counts as good advice. Although I've been building PC's for more than 10 years, most, if not all, of my PC's rarely date past 2005.