Hi Everyone, Just a (long) post to share my experience installing a 2nd Intel Xeon E5462 CPU inside my Early 2008 Mac Pro Quad 2.8GHz. I know there already are guides to upgrade 1st gen Mac Pros, but I couldn't find anything for the quad 2.8GHz (and also it's an excuse to share some Mac Pro nude hardware pr0n pics ). So, this is the beast with a 8800GT (with an Accelero S1 Rev.2): That is what I'm going to install : The first thing (after disconnecting everything) is to remove the disk drives, and remove the cover of the CPU heatsink (which is magnetically attached, pull it with your fingers from the bottom, near the logic board) : Then, remove the front fans assembly thing by removing a screw at the top of the motherboard (between the fans thing and drive bay 1), and another one at the left of the top of the bottom CPU heatsink (the only one present in the Quad 08 Mac Pro). You can then pull the fans away. Now we can clearly see the bottom CPU heatsink, and the dummy one on the 2nd CPU socket: Now, I believe you could directly remove it if you have the proper tool (long handled torx screwdriver). But since mine was missing something like half a centimeter in length, and that the magnets of the CPU cover support were messing with the removable screwdriver head, I had to remove the memory cage to better access the heatsink screws (Apple also recommends it, not sure why though). So, the memory cage is removed by unscrewing 4 screws near the logic board: ... and two screws at the bottom of the case ... ... and sliding the fan of the memory cage inside it, so you can vertically get it out of the cage of the Mac Pro (otherwise you can't, it's blocking). Be aware of the fan connector (under the cage), don't forget to plug it back when reassembling: So now we have a complete access to the Mac Pro logic board, and we can unscrew the dummy heatsink. it's also time for some nude Mac Pro pics: Let's insert the new CPU, and attach the heatsink: While you're at it, don't forget to plug the heatsink thermal sensor to the logic board, otherwise I'm not sure the Mac Pro would like it very much. But wait, isn't something wrong? That's better! I also took advantage of having the front fans removed so I can get cables into the ODD SATA ports, preparing for the future use of SSDs in RAID0 in the bottom drive bay (not in the immediate future though, I'll wait for a serious price drop first). Then it's time to put everything back together: I also took the opportunity to remove the Accelero S1 sticker. (What is this, a PC? ) And I'm happy to report that the patient has survived, and is accepting the transplant! You can find more pics at my flickr set. Hope you enjoyed it!