Blue Screen w/ dmp file

Today I had dell through warranty exchange my old ram and video card. Then after a while of gaming (pc performed fine) my game randomly crashed and i had a windows error. "the instruction at 0x00dfde9f referenced memory at 0xcbc70576. the memory could not be read. Then i re-launched the game, same error came up and as i opened event view i blue screened. I have attached the dump.

What is happening exactly? Thanks in advance.

To add a bit more detail, they switched out my 2 GTX 260s for 2 460s, and replaced my 6gb of ram with 12 gbs. I dont know if it matters, just adding in a bit more info

I'm currently running the Memtest86 atm, however as it displays the brand of my sticks I came up with a question for you, I'm not entirely sure but is using different brands of sticks not the greatest of ideas? Or does it generally not matter? Im seing they replaced my sticks with 2 Samsung M378B5273DH0-CH9, and then the third stick is Hynix Semiconductor HMT351U6CFR8C. Thanks if anyone answers that,

I will post the test results when the test is completed.

So im still running the test, for a while pass was at 1, and then 3:56 minutes in the errors started rising at incredible speeeds. its at 210 now. lol. So its fair to say they gave me bad sticks?
37,000....yeah im gona call Dell...

Appreciate your help for directing me in the right direction. Theyre sending me another batch of video cards and a MOBO, if that doesnt resolve it theyre sending in more memory sticks as well. Since my PC wasnt as bad before they replaced the parts.