Can someone tell me what the problem is , I installed a new heatsink " Artic freezer 7" and now my computer turns off when i start it and when the computer decides not to turn off, I have no sound on my computer , can someone tell me why it turns off and what i can do about it,Also why is there no sound on my computer, what can do about this problem also?

Well, if you had no problems up until now, it sounds as though the heatsink isn't firmly in place or there was no compound used. This is just an assumption, but a lot of cpu's will either slow down immencely or turn off to prevent damage. Can you give us a little more info on your system? What chipset etc. As far as your sound goes, I'm not to sure. Did you make sure you grounded yourself before touching the inside of your system. Static electricity can easily kill a pc, or at least parts of it. Double check your heatsink though first, make sure it's seated in place and not fetched up on the mount and that you have some compound between your cpu and heatsink. (Artic Silver 5 works very well)

I think my chipset is intel p4 LGA775, I mean sometimes it works , i fixed the sound the speaker plug wasn't put on appapratite section.