Hold down the Option key as you start up. An All-in-ROM routine called the Startup Manager will draw an icon for each potentially-bootable volume it finds. If the new install is found, select it and proceed. When MacOS X comes up, use
System Preferences > Startup Disk ...
... to set the Startup Disk again.
I've already tried that. Oddly enough, sometimes it will not see the new HD in the SATA to USB, until I go into DU, and it won't allow me to go to the startup manager with just the new HD in. But when I set it as a startup disk while it was in the SATA to USB, it did show up in the startup manager, and it did boot correctly. Then I swaped it with the old internal one and it couldn't see it again!
I just flashed the NVRAM (twice) and that didn't work either...
I do have a question, if I were to flash the NVRAM would I need to THEN set it as the startup disk? or would simply flashing the NVRAM with ONLY the new disk in it work? Because I only did the latter and got the flashing folder and "?".
MacOS X does not have default Startup disk after you reset NVRAM until you manage to specify one.
Nothing should preclude you from using Startup Manager. It is all in ROM. Nothing needs to be loaded from anywhere. It should work with no drives present (it is useless that way, but it still does its job).
If you are not getting the Starup Manger, you Mac has a very fundamental problem.
If Startup Manager is working, but you are not seeing that disk in Startup Manager, the drive or the image on it has some problems. Sometimes a Disk Utility ( Repair Disk ) will set them straight. You can do that from Recovery_HD.
"MacOS X does not have default Startup disk after you reset NVRAM until you manage to specify one."
Whoa whoa whoa, hang on. I'm not sure thats correct.Where did you get that?
Because after my experiment didn't work I put the old HD back in, and it booted up fine and everything without me having to designate a new startup disk after wiping the NVRAM.
Also, it is like I stated before I boot up the machine with the NEW HD attached via SATA to USB, and the OLD one is in its normal position. The startup manager does not usually see the new disk until I go into the DU or the "Startup disk" in the upper corner. Yet when I verify the disk it says everything is working fine. And its a NEW HD that was purchased several days ago and is recognized by WINDOWS every time as a GUID formatted, HFS+ formated disk.
And if you think this is a problem, it would be beneficial to elaborate on what you think the problem is, and how I could conceivable fix it.