How do I remove heat-sink & processor from mboard. Is the heat-sink removed with or before processor??

If you're replacing the cpu because your computer isn't working properly, it's quite rare for a cpu to fail or even malfunction unless it's cpu fan has failed, or it overheated for some other reason such as the heatsink was clogged with mung, or you did something else dumb yourself that damaged it - almost always your real problem is something else. Tell us your symptoms in that case. ........ See the User's manual for your model or model series. It's probably available on the HP site. What that may not tell you is the heatsink may be firmly stuck to the cpu. In that case, after you have unclamped the heat sink from the cpu socket, with the case lying on one side so the mboard is horizontal, press firmly straight down on the heatsink/cpu, and try twisting the heat sink back and forth while still pressing down firmly , and the heatsink should eventually come unstuck from the cpu. Then you can easily remove the heatsink from the cpu, and move the lever beside the cpu socket to easily remove the cpu. If that's not successful, clamp the heatsink down again, make sure the cpu fan is connected, and run the computer until the cpu has warmed up to at least a stable idle warmer temperature - run it for at least 15 minutes - then try again. If you still can't get the heatsink off the cpu, take the computer to a place that works on / repairs computers to see if they can get the heatsink off the cpu - they have a lot of experience with dealing with that. If you upgrade to a different cpu, the heatsink/cpu fan combo must be able to adequately cool the cpu - the combo that came with the original cpu may not be adequate. If you get a boxed set that has the heatsink/cpu fan included, that combo will work fine. If you get the cpu by itself, a third party combo that will handle that cpu will work fine. ........ If you want us to find out which cpus you can use specifically, say so.