I’m going to back-track a bit here. I’d love to give a bit of back-story to this modding adventure, and wanted to share my experience thus far.I came by two dead G5s last week and already dove in head first. When I received these as a gift from IT, I was told one had a fried motherboard...err, logic board..and the other just had something wrong with the SATA connectors. I set the SATA one aside thinking I could try to get it running in the future, but knew the one with the fried motherboard had a different fate.I knew nothing about the specs or hardware of either of these machines, and I’ve never worked inside an Apple computer before. The experience of getting to comb through the G5 and really get my hands dirty is the sole reason I took the machines. For years I sort of considered these towers to be the holy grail of computer case architecture. Although I have no interest in PowerPC technology and despise the Mac OS, the layout of these G5s and of course the newest Mac Pros is obviously desirable.The one on the left is without a double dual CPU, but I figured since the right one only has one CPU cover I just assumed it was a single CPU......wrong! I was amazed to see a propriety Apple water cooling system cooling two CPUs. I had heard that they implemented this under the hood, but I never thought one of my freebie machines would of contained it.Time to start stripping this beast down. I just unscrewed everything I could see on the CPU cooler, which ended up including 4 different screw types. Good thing I came prepared. The CPUs appear to be mounted on individual cards beneath the heat-sink(s), and I’m intrigued by what appears to be the power cables.After about 40 minutes of fussing and shedding about 25 screws, she finally let go of her cooling block. The CPU sleds (is that the right nomenclature? sounds right to me...) came off as part of the same heap.This thing is a BEAST.They connect to the logic board using these oddly arranged CPU pin grids. The power connections are equally unique. The four silver leads on the right side of the case are for the CPUs, and the logic board gets its power from 8 leads protruding directly from the power supply along the bottom. Never seen anything like it!After another 15 screws, the motherboard is finally released.This thing is crazy huge, and has a lot of unique features.I love these heat sinks on the bottom of the board...Here is the I/O panel...more on that later...With the power supply cover removed, the very long and flat 1000W power supply is revealed.This thing had to be squeezed out fairly strategically. It fought back but I prevailed. It’s gotta be about 15 lbs.This junk up here was a real pain to get out. I ended up having to remove the heat-shield which I was not planning on doing. Although I then realized it would have to come off eventually anyway, because I plan to mount the ATX PSU where the hard drive slots currently are.After about 2 hours and at least 50 screws, she is finally bare. Still some cleanup to do inside though. I went on to unscrew as many standoffs as I could, but was forced to resort to a few taps of a hammer to dislodge some which were glued/melded on.Lots of parts laying around.A speaker on a fan. Only Apple...LOTS of fans actually. I normally don't see G5 modders utilize these, but my initial plan is to use all of them. I understand the wiring may be a bit wonky, but should be fairly straight forward I would think... We'll see!Ok so that was definitely a blast, but now it’s time for some new hardware. I got these cases for free, and I am not planning on spending any money on specific hardware. I have several older machines laying around collecting dust (very literally), so I’m just going to use one of their guts.Here is the donor...It's a Gigabyte GA-M57SLI-S4 with an AMD Athlon 64 X2 6400+...She's an oldie I know, but I just finished building a new Sandy Bridge 700D rig and have no desire to purchase new hardware for this mod. I got the G5 case for free, so I'm just recycling this old AMD system I had laying around. It'll be making sure to leave everything generic enough so that any standard ATX board could be swapped in one day.Here is it tested in the case:If you missed me say it earlier, I am planning on using a flexible PCIe extension ribbon to connect the GFX card to the motherboard.Here is another test fitting of the stock coolers. I plan to use them all as long as I can rewire them to work with ATX.Since I took those photos, I've reconsidered putting the PSU in that upper right corner. I am going to do some test fitting in the lower left corner. I might need to remove it from the casing but I am hoping to avoid that.And one last shot of what has been keeping me going so far...That’s my progress so far. My next step is going to be testing that PCI Express extender. I should make sure that is going to work for me before I go on, considering the entire configuration depends on it.Planning cable routes and ordering other necessary extensions and ports will also be a critical part of the next step. For USB, firewire, and audio ports I will be yanking the front panel connectors out of 2 spare cases I have laying around. It should be fun fabricating brackets to hold everything in place.I will also be either fabricating a custom motherboard backplate, or trying to utilize one from one of my donor cases.I’ll also be re-using the second stock Apple heat-shield to separate the GFX and CPU cooling zones.The hard drive(s) will probably be mounted flat against the bottom of the case.I’m considering painting the case black. It’s still very much up in the air