Mac Pro 4,1 (2009) restarts and is crippled by Bootcamp once a HDD is selected

Intro + past questions:

Hi guys. I've asked a few questions on here now about this same device so I will connect those questions so that you can have a lil more info to fall back on just in case they are somehow related:

https://discussions.apple.com/thread/252018688?answerId=253845410022&replyId=253845410022

https://discussions.apple.com/thread/252026602?answerId=253855005022&login=true&page=1

Question:

I have a Mac Pro and I'm trying to run bootcamp on it. I saw in a another thread (https://discussions.apple.com/thread/8092726?login=true&page=2) that USB3 apparently did not work. I'm running a diff operating system than the person there. I actually thought I was running El Capitan in all the questions I asked but just saw that I'm running Yosemite!

I was using a USB3 to do all boot disk things, but I'm not sure if that's the issue.

Story:

When I first got the computer, used a couple days ago, I had a HDD with a real version of Windows XP... like it came from a standard model Windows XP computer that I salvaged from the trash. I put that in one of the bays and tried to boot to it. It showed the XP logo but then it failed right after and it had to be restarted back into Mac. Nothing crazy

Fast forward I get home and I ran into this issue https://discussions.apple.com/thread/252018688?answerId=253845410022&replyId=253845410022 .

I got it fixed by putting in my USB3 flash drive in as an installer for El Capitan (I thought that's what I was running) and it began to install but then instead it just reverted back to my normal login screen.

I was home free.

This time around I formatted all the extra disks that I had to prepare for doing everything properly using bootcamp. So I forget what I formated to exactly but I'm p sure one was ExFat , my normal one was os journaled and the xp one for formatted to something but that kept failing on formatting and kept leaving evy partition unmountable. Could have been a faulty hard drive, or it could have been my MAc PRo that did to it I'm not sure.

So I'm using bootcamp. I'm watching videos online and I notice that ppl are saying that they have to go into textedit in order to adjust setting to allow bootcamp to let them install from a usb and to install windows 10 at all. I don't have that issue, which implies to me that someone already did this process maybe. I go through and try downloading the windows support files but it's taking long so I gather the ones I saved on my other computer and bring them to the mac pro manually.

I go further in boot camp and get to the point where I have to choose a disk. I choose this SSD that I have that hasn't shown any issues before and IMMEDIATELY after pressing continue boot camp closes and the computer closes all apps and shuts down and give me the issue as described in (https://discussions.apple.com/thread/252018688?answerId=253845410022).

I let the computer sit for the night and came back this morning and was able to use the same OS Snow Leopard grey install disk (after removing all other hard drives and externals and anything else and also leaving it unplugged all night and holding 'c' on startup) to bring it back to the page with time machine. This time I have a time machine partition though so theoretically this process will be smoother (I'm about to install rn to another disk so I can have two versions and not be afraid clearing the disk and then the time machine not working or something idk. There's nothing important on it just to be safe.

What I need:

I need to get boot camp to work on the computer. I got the computer for a small business I have and I need windows and mac for that business.

Any suggestions?