Check your power supply that the fan is working.

My money is on that being an OEM piece of junk..... it's not enough (the smell is the PSU). Get a good one before it starts taking your hardware out.

Oh, also the voltage coming out of the wall could be not so good.  It happens more often than you might think.   They've got $20 voltage regulator things you can plug into the wall, which for really expensive integrated circuitry is probably a good idea anyway.

Thanks for all the replies Ill try change that out.

Any tips on what brand is a good PSU???

The one in the system now is a bit dodgy came with the case

Iv had the system for 3-4 years and never smelt that......also seems strange to me its only during the one program but for everything else operation is normal.

@tetleytea. Thanks for the explanation.....when you say "would certainly make things worse if allowed to run that way".....do you mean in general even when no smell is emitting. Or should i just turn the thing off when the smell eminates which is only when im running one program. (So ill just not run that program)

I will upgrade the PSU asap. Hopefully its not to tricky. Never changed out a power supply before. Dosnt look to hard.

Thank you all again. Glad there is a general concesus that its is the PSU and not 10 million diff responses.

Much love. Will let you know if it fixes the problem. Cheers

personally I've had very good experiences with the brand 'be quiet!'. My brother lives in a flat with very unstable power (voltage fluctuations) and I used to have to replace his PSU every 3-6 months. now he's had one from be quiet! for nearly 2 years without an incident. I myself haven't had a defect PSU ever in my flat (nearly all of them be quiet!) since about 8 years, but my power lines seem very stable so a cheaper brand might also have worked. If you want truly perfect and stable power, buy an online UPS - but they are rather expensive

If you're getting the smell, then you're definitely letting things get worse if you keep running it like that.   If you're not getting the smell, things will probably still get worse over time, just not as fast than if you were smelling things.

Integrated circuits nowadays--particularly the video card and the CPU (but also some chipset components)--use a technique called DVFS to conserve power.  Based on the demands on the card/CPU, it can ratchet down the voltage and the clock speed in real-time so it runs less hot and burns less battery (which is why it was invented).  Running different software can cause your voltage levels and clock speeds to change.  So if your voltage is poorly regulated--but the PMU (power management unit) says not to run at full voltage--you don't have a problem.  But if you run that one app that needs top speed and voltage--and the input voltage is poorly regulated--the bleeder diodes on the CPU's pad ring will short out, and that is a very BAD thing!!   Besides burning your CPU packaging to a crisp, that means you are running your CPU at 0.5V higher than it should be.   And CPU's only run at 1.3V.  Even if you are running at 0.4V over what you should be, that'll seriously shorten the life of your CPU, and you won't smell anything then.

Thanks for the advice guys. Changed out PSU last night to a Corsair TX850......working like a charm. Ran the problem child for about 2 hours and no smell.

Sux i had to fork out the money. But now i know my power supply wont kill my poota.

Have edcited the OP subject line to SOLVED. @yrag your a champ dude. Saved me so much time with your Corsair TX suggestion. Cant thank you enough and also @Tetleytea your imput put my mind at ease.

Very relieved the issue is solved...thankyou all.