This post is a summary of my build thread shown here: http://forums.macrumors.com/showthread.php?t=1564660 Have an old 2006 4-core mac pro and a couple hundred bucks laying around? If your good at hunting on ebay you can make that old 2006 machine into a 2008 with a simple swap of the logic board and processors! Tools/necessities: -Extra long T15 torx bit (about an 8 inch reach to get to the heatsink screws) -T10 torx -Various philips and flathead screwdrivers. -Thermal Paste -Coffee filters (used with thermal paste application) -Paper towel (cleanup for whatever reason) -Isopropal Alcohol (at least 95%) Useable 2006 parts: -Case -Power supply -Ram (but NOT the 2006 ram risers) -Optical drive and complete tray -Hard drive Trays -Front fan (sort of) -Cpu cover (sort of) -Front IO board on case -Front speaker -Bluetooth card -Airport wifi card Parts you will NEED: First, naturally you will need a 2008 Logic board and 2 matching cpus to fit that board. I went with the stock 2.8 ghz xeons that originally came with it. 2008 memory cage with rear fan 2008 northbridge heatsink 2008 Wiring Harness: PN 922-8501 593-0619-A. Lastly 2008 riser cards for the ram. You will see below that the 2006 ram risers do not fit in the 2008 memory cage. Things you wont need but may want to make it "perfect": -2008 Front Fan Assembly -2008 cpu cover These are not require for it to work, but the fit and finish wont be perfect as I will show you below. Dissassembly As you can see I opted to get a brand new 2008 case, this is not necessary but I wanted a new to me machine as far as case condition goes. First we must take apart the 2006 unit. Start by removing all of your smaller components such as the hard drives, front fan, front speaker, ram trays, optical drive tray, cpu cover, and graphics card. Dont forget the Airport card and bluetooth card if you have these as well. After those have been removed it is time to remove the old 2006 memory tray. This can be a difficult task as the plastic riser holders and rear fan snaps are very tough to undo. Use a plastic card or something to slip between the two to break the snaps apart so you can move the plastic holders inside to have more room upon removal. If you dont think you have the room, you should be able to remove the cpu heatsinks first to make life easier here. If you have a new case DO THIS STEP if not IGNORE this step if your keeping your old case: Next take the T10 torx bit and remove the 4 screws holding the power supply in place (above the graphics card area you will find these mixed in with the Philips screws...don't worry about the Philips screws, no need to remove those) With all the smaller bits removed you now have full access to the actual guts of your system. In this order use the long skinny T15 torx bit to remove the cpu heatsinks from the 2006 board. Upper CPU first, then lower cpu second. With everything listed above you should now have a case with nothing but a logic board remaining inside of it. If you got a new case, you can leave this case be and sell it//whatever you please with it. If you dont have a new case, then your not done yet! Remove all data and power cables from the logic board then prepare to remove the old logic board! Take note of the black Philips screws holding the 2006 logic board in place before you remove them. Remove the remaining screws, slide the logic board towards the front of the case, and carefully remove the board from the case! Dissassembly complete! Next step; assembly! First thing you must do is secure your new 2008 logic board in your old or new case. Simply carefully lower it in place, and slide it back so the rear IO goes into their holes, then screw it down. Dont put any screws in the 4 memory cage holes for the 2008 memory cage, it has its own built in screws. Once the logic board is secure plug in all the data and power connections you previously unplugged from the 2006 board, if not, your new case should have them already inside as mine did already laid out and ready to go. If your new case doesn't have these, you will have to transfer all your old cable over to the new case if you have a new case without cable. After the board is fully in and plugged in, its time to prep and install the 3 big heatsinks. In the image above I had done this in the wrong order. I ended up having to remove the top cpu heatsink and get the bottom one in first. I used the method of cleaning the heatsinks off with the iso alcohol and coffee filters to get them perfect before install. Following the cleaning I made a big + on each processor/north bridge as shown above, then I also put a dab on each heatsink and spread it around with a coffee filter to make a prep film to fill the pores in the conductive surface. I wont get into detail here, just look up Artic Silver's guide to prepping and installing heatsinks. All I can say is BE CAREFUL if your using a conductive thermal paste as I did. If you drip any of it on the logic board it can create a ground between different parts since it is conductive, and cause major problems or even destroy your new logic board. Heatsink install order: Bottom cpu Northbridge Top cpu. Once those are in, install all the smaller parts you removed in the same order you removed them. After taking the 2006 apart you should be able to tell how to assemble it! When your finished your final product should look like this: This is where I said you need a 2008 front fan and 2008 cpu cover to make things fit perfectly. I am living with it like this for now until I find a good deal on those 2 parts on ebay. Only serious issue after this build, my front top fan as shown here: http://www.youtube.com/watch?v=drrtq_UmEqc&feature=youtu.be It is unnecessarily loud so I just unplugged it. I believe its because the 2008 fans are slightly different and the 2008 logic board's fan controller doesnt like the 2006 fans for some reason. My system is fairly quiet with that top fan unplugged, and my temperatures are great. 28-29c at idle, and when rendering it maxes out at 45-46c. If you made it this far, thanks for reading! If you actually followed my guide and converted your 2006 into a 2008, even better! This conversion isnt really hard with the correct tools and some past experience building custom gaming desktops//computer assembly in general. My Final Costs (US dollars): Ram risers: $35.99 shipped Northbridge heatsink: $24.95 shipped Motherboard & cpus included: $305 shipped 2008 memory cage: $24 shipped Total: $389.94 New case cost me $150 + 65 Shipping. That was not a required thing but an extra.