I've been having a problem booting from this one HDD inside my Mac Pro for a few weeks now, and I have no idea why. Let me start off by stating what happened before this issue started. I have 4 OSes installed on this comp: Windows 8, Windows 10, OSX Yosemite and OSX El Capitan. While I was running the Win10 boot without any issues, I was running low on space in this partition so I decided to shrink the Windows 8 partition by 40GB. While that was successful, I couldn't extend that space onto the Win10 partition because it was not contiguous (I had no idea that was going to happen). So I didn't end up formatting it because I needed to restart my comp since Windows was bugging out (because Windows is always broken in one way or another). So instead of booting into Yosemite by default, it goes straight to El Capitan as if none of the other OSes or partitions were there! I don't remember how all the partitions were spread out across the HDDs I have installed. I just know that I really need to get back into these OSes because many valuable development projects are there. What have I tried? I've tried going to bootchamp and it didn't recognize any other paritions. I tried restarting and after getting into El Capitan, it told me that it didn't recognize a disk (which is apparently bad). Now, what I WOULD try if I could would be to hold the appropriate key during startup, but since I am using a stock video card (non-Mac EFI) I can't actually see that screen so it wouldn't really help. As a last resort, I can take out my HDDs, put them into my HDD caddy and plug them into other comps like my Macbook Pro or Laptop and see if they can read it. I'm really lost here. And of course, this really sucks. Any ideas? Thanks. Shogun.