Hi Luxus
You have mentioned a common problem area with the latest motherboards, but I tend to add a Graphics card in the EX_PCI slot as that helps the processor run normal programs better by taking the load of it.
I tend to get a lot of comments from my Customers saying "you said this machine would be faster and it seems the same as the old one" this is purely down to memory, Hard drive and Graphics processes, so I now tend to hive off what I can.
But I can agree the Intel chipset can cause a lot of problems, and some of microsofts Virus deterents are to stop certain writes to certain memory locations, thus making this even worse.
In my case the shutdowns were definitely fixed by replacing the Hard drive, but in others this could be the problem.
To answer your question, I have not added an extra graphics card in this machine, and it is using the on board GPU, but replacing the drive worked, so it was not the onBoard GPU that was causing my problem.
It certainly was not the OS either, as others have suggested.