Hello All, So, I am the original owner of a very reliable and well-deserving 2006 Mac Pro 1,1 Here's a little story of my history and recent upgrades. Geekbench 3 and temperature comparisons at the bottom. I purchased this machine new, having been through numerous Apple lemons at the time. I gave up on buying machines, and sat and waited for them to produce a machine that didn't have any complaints (got tired of being the guinea pig). So, after a full year of the 2006 being on the market, without any complaints, I took the plunge, and purchased the 2006 model just before the release of the 2007 model. I wasn't taking any chances. My 2006 Mac Pro has been an amazingly reliable machine. Never failed once. No problems. Always worked. But, eventually, time catches up with us, and we find that our faithful friend is being shunned by newer software (unsupported). I made it until last year (2015) with Snow Leopard. And, finally updated to Lion. But, of course, with a 32-BIT EFI, I couldn't go past Lion without some tweaks. And, found myself unable to run many titles that I wished to use. So, now in September of 2016, my 10 year old computer has gotten some well deserved updates and tweaks. It's now back in the game, with modern software and revived performance. Up until this last month, my machine served it's 10 years with me in a fairly standard configuration. Factory two 2.66 GHz dual cores. Moderately upgraded RAM (11 GB), the factory nVidia 7300 GT, and roughly 1.5 TB of hard drive space. The machine's new lease on life comes with a long desired CPU upgrade, and memory, plus a few extras. Resulting in a machine with Dual 3.0 GHz Quad Core Xeon CPU's (5365) for a total of 8 cores, an nVidia 8800 Ultra w/ 768 MB of Video Memory, 32 GB of matched memory modules (w/ large Apple approved heat-sinks), 20 TB of hard drive space (between internals and externals), dual superdrives, 120 GB SSD with OS X El Capitan 10.11.6, 128 GB SSD with a native install of Windows 10 Pro 64-BIT, and one extra PCI slot venting fan installed. The dual SSD drives are installed along side the DVD drives in the top of the case, and utilize the two extra SATA data ports on the mainboard (I powered them internally by adding power splitters to the DVD drive's power connection. The extra PCI slot venting cooling fan is powered likewise. I have not increased the speed of any of the factory cooling fans. The CPU's are mated to the heat-sinks using Arctic Silver 5 thermal compound. I spent considerable time refurbishing the surface of the 5365 Xeons that I purchased from e-bay (I was not happy with what I found when I opened that package - what a mess). Looked like someone had attempted something crazy with the surface. There was no cleaning that surface, I resorted to sanding and resurfacing it. But, I did NOT do any "delidding". The factory CPU's in the Mac Pro 1,1 had their lids / heat-spreaders on them, and therefore I saw no reason to go into delidding on the upgrade CPU's. I considered the various methods of heat-sink compound application, and in the end, decided against the straight line, the pea-sized dot, etc.... And, instead went with the very thin, evenly spread layer over the whole CPU (staying only on the mating surface). I arrived at this by 3 ways, one: I spent years installing CPU's and building machines, and always did it that way with no problem, and two: Apple had merely used a thermal pad (but it covered the whole surface), and three: I understand that the pea-sized dot squishes out, and spreads as you press the heat-sink into place, but I have likewise removed CPU's installed this way and found a significant amount of the surface essentially "unmated". So, I went with experience over the recommendations. And, applied a very very thin evenly spread, and smooth layer over the CPU's mating surface. Naturally, I did "tint" as in worked-in some thermal compound into the surface of both the heat-sink and the CPU prior to applying the final coating. This is to insure that all the microscopic pores / grooves in the surfaces are filled with compound to essentially provide a perfectly smooth and fully even mated connection. The end result? Everything is running much much cooler than the factory original 2.66 GHz Dual core setup, and obviously, much faster as well. You can view my performance comparisons between the factory setup, the upgraded setup, and of course both with Lion and repeated with El Capitan for good measure. And, naturally also a Windows 10 comparison of both configurations also, in my geekbench profile at: https://browser.primatelabs.com/user/90296 Note that the geekbench 3 results will show more comparison points for my machine at different stages / configurations / operating systems. You can also view my temperature comparisons in the attached files (Note: only 2 hard drives and one SATA were installed during testing - same ones for consistency). For those considering such an upgrade, I hope that you'll find the above story and attached / linked information useful or encouraging. The process is not hard. Just take your time, work slowly, pay attention to how everything came apart. The results are worth it. The best part, my reliable machine feels like a brand new machine. Fast, smooth, and best of all... still reliable. No gambles on new machines. I find myself continually pleased with how well my decision paid off in 2006 / 2007. This machine has put in many years, and is still very relevant today. It still did everything I needed prior to the upgrade, and was relevant in the market compared to newer Windows machines (running Windows 10, I could still use it with modern software). And, now, with it's new tweaks and upgrades, I expect I'll get many more years of use out of it. I got 10 years as it was, and most of them with Snow Leopard. I expect I'll get many more years out of it before El Capitan becomes as obsolete as Snow Leopard is now. Either way, the performance is still great, and the upgrade was worth the time and small expense. And, for those of you looking to get El Capitan on your machines, or finding yourself looking for parts that will support El Capitan on your 2006 Mac Pro's, be sure to check out: http://old-macs.com/ He had many of the parts I needed, saved me a lot of hassle on the El Capitan install / EFI 32-Hack, and was extremely helpful, fast, and easy to work with. My best online purchase experience in years. And, he packs his products extremely well for shipping. I was impressed. Anyway, if you have any questions, feel free to ask. Hope the above story is of help to someone.