thermal paste?

hey guys, i just bought an evga 780i SLI mobo (upgrade from dell's crappy 650i SLI mobo) and the cpu cooler on my Q9300 is huge and it screws in. i didnt know they were made also to screw in, anyway i go and replace the mobo and go to put the cooler on and it doesnt fit the screw holes that the cooler uses. so now i have the cooler on as best as i can get it with the side of my case open and a fan blowing air in it, if dont use the fan the cpu will run for maybe 5 minutes then the pc shuts down. and if i dont use the cpu cooler and use just the open case and fan the pc shuts down during post, so using both at the same time is working but im not gaming/overclocking ( which is why i bought the new mobo in the first place) until i replace the cooler. but the question is this, how do i remove the previous thermal paste off of the cpu? or should i leave it there and when i get the new cooler will it will be fine? should i buy some thermal paste and re-do with the new cooler? if i need to remove the previous paste what should i use? any help is thanked in advanced, cause i really need help or im gonna melt my cpu. the cooler and paste i am buying is this

http://www.newegg.com/Product/Prod [...] 6835186134 is the cooler

http://www.newegg.com/Product/Prod [...] 6835100007 is the paste

i know the cooler is arctic 7 and the paste is arctic 5, does that matter at all? thanks for all who help a fellow pc builder/gamer (ive built only one pc and i games flawlessly, im not an expert yet)

Never turn on the PC with no heatsink, ever.

The reason the AC7 dosent fit on your board is probably because of that ridiculus NB heatsink that nvidia boards have, check for clearance issues.

Try rotating the cooler and see if theres a direction that makes everything line up. The holes are universaly spaced for Skt775 so it will fit if it was on the old board.

Also as mentioned this may be a clearance issue with the NB heatsink.

Thats because your Dell motherboard was a propritary design. Youre going to need to remove that backplate and buy a new HS

Sorry pal. but if you can RMA that CPU too then do it. You might have fried it and it will die soon, or more likely shaved around 80% of its lifespan off. Most of the time a CPU without a heatsink will totally burn out when it is turned on even for a few seconds! Overclocking is most likely not an option. Hopefully you will get a couple of years out of it, but overclocking will lower that a good bit, even at nice temps. To remove thermal paste use 70% or greater rubbing alcohol and lighty wipe it away with an alcohol damped Q-tip or coffee filter. Make sure not to EVER touch the sides or the bottom of the CPU with it. If you overclock (I assume you will ignore my warning, it happens) then you should read up on it. You should know (but might not) that you should NEVER let the CPU cruise over 65c. The PC automatically shuts down at 110c with nVidia chipsets so... just be careful and maybe save for a new CPU just in case. Don't blame dell (can't believe I just said that), it is nVidia's fault since their 600 series motherboards had low quality voltage regulators, and well they are totally low quality.