I'm determined to make the best of this Mac Pro that I can (within limits). For example, ram. I just got in an 8gb set from an amazon vendor. After inserting the two sticks onto the ram boards it only shows 4gb, the size of 1 stick. I used the apple manual to add memory. One stick to each ram board and in the same position, furthest in socket.
Next, the system info reports the model as 1,1. It's a 3,1 but it won't upgrade past snow leopard. How can I get it to El Capitan or maybe High Sierra ?
Is Amazon's drive tray converter to 2.5" the best ? I already have a 250gb SSD that I've love to put in. I'd like to use other drives I have as well, but even with the snow leopard formatted drive out, it won't boot into high sierra.
If answers to these questions are available elsewhere, please let me know!
Are you sure you have a 3,1? You can check your Mac Pro's product code at the back panel near the expansion port slots. It's printed there as to what Mac Pro you have. It should say A1186 EMC2133 for 1,1 or A1186 EMC2180 something for 3,1. Secondly, to install Lion, you need an OpenCL graphics card like the Nvidia GT120 or the Radeon HD5770. These 2 cards will allow you to take the Mac Pro 1,1 to Lion and 3,1 to El-Capitan. There are hacks for the 1,1 to go up to El-Capitan by flashing the firmware to 2,1. Whereas the Dos Dude hack allows the 3,1, with the appropriate Nvidia metal based card such as the Nvidia GTX770 with Mac firmware if you want a boot screen(fastest card you can put in 3,1) to go to Mojave. So with the Mac Pro, what video card you have in it dictates how high the OS you can go up to. You should have at least 2Gb or 4Gb of RAM also to begin with. Both the 1,1 and 3,1 have older stock cards which you will need to swap out. The 1,1 has the GeForce GT 7300 and the 3,1 has a stock AMD 2600XT. If you open up the side case and take a look inside and check the graphics card and if you have a GT7300, then you more likely have a 1,1. If you have a 2600XT, then you might likely have a 3,1. The system profiler usually don't lie. If you have a 1,1, then you have a 1,1. What type of RAM did you get? Did you get the PC-5300 DDR2 ECC (667Mhz) or the PC-6400 DDR2 ECC (800Mhz)? The 3,1 uses PC-6400 DDR2 ECC version.
In regards to drive trays.. I don't use drive trays on my Mac Pro 5,1 for SSDs so I can't offer any thoughts on what's available on Amazon. SSDs are often light enough that you can just add a 3M velcro sticker (that you use to hold up picture frames with) which you can buy from either the dollar store or a hardware store to hold the SSD in place after you inserted the SSD drive into the SATA port.
For further questions, you might want to post in the dedicated Mac Pro forum where you have more experienced users and hackers who had upgraded their 1,1 and 3,1 to the max.