Hey, Thanks for taking a look. I will try to explain this problem as much as I can, hopefully someone will be able to help me 
I currently have 3 HDD's 2 in my New PC (couple of months old) 1 in old PC
New PC
1 x 1TB
1 x 2TB
Until today, my PC was working fine, today I decided to reformat and reinstall Windows 7, all went smooth. Once It was installed I realised my 1TB HDD wasn't showing up, the 2TB had the OS on it before and I installed it on the same HDD again.
So I went into BIOS and realised that the 2TB one is the slave and 1TB the master, I thought If I disconnected the 1TB and booted it would make the 2TB the master, this is where the problems started.
Once I boot up, it shows the main Mobo screen, then it goes on to a blank screen and says "Loading Operating System" and just hangs there till I switch it off, so I thought ok, maybe I should install the OS again with just the 2TB connected, got up to the bit where it switches off your PC to finish the installation and then on reboot, the same problem happened.
Then I tried to connect the 1TB HDD only and install the OS on that, wont let me do it, every time I press F12 to choose boot from CD it will restart, same thing happens if I try to enter BIOS or perform Xpress Recovery.
As a last ditch attempt, I took out my old HDD from the other PC, same thing happens wont work at all.
Now the interesting part. The 2TB HDD which wouldn't boot up after the PC restarted in the middle of OS install. Well I put that in my old computer and started it up, and to my amazement it finished off the setup and was working perfectly, so I'm guessing something has happened to my Mobo?
Anyone know what I can do/try to get this problem fixed?
I have a Gigabyte UD4 Revision 3 Mobo which I bought in April.
Would really appreciate some thoughts on this.
Thank you very much

I currently have 3 HDD's 2 in my New PC (couple of months old) 1 in old PC
New PC
1 x 1TB
1 x 2TB
Until today, my PC was working fine, today I decided to reformat and reinstall Windows 7, all went smooth. Once It was installed I realised my 1TB HDD wasn't showing up, the 2TB had the OS on it before and I installed it on the same HDD again.
So I went into BIOS and realised that the 2TB one is the slave and 1TB the master, I thought If I disconnected the 1TB and booted it would make the 2TB the master, this is where the problems started.
Once I boot up, it shows the main Mobo screen, then it goes on to a blank screen and says "Loading Operating System" and just hangs there till I switch it off, so I thought ok, maybe I should install the OS again with just the 2TB connected, got up to the bit where it switches off your PC to finish the installation and then on reboot, the same problem happened.
Then I tried to connect the 1TB HDD only and install the OS on that, wont let me do it, every time I press F12 to choose boot from CD it will restart, same thing happens if I try to enter BIOS or perform Xpress Recovery.
As a last ditch attempt, I took out my old HDD from the other PC, same thing happens wont work at all.
Now the interesting part. The 2TB HDD which wouldn't boot up after the PC restarted in the middle of OS install. Well I put that in my old computer and started it up, and to my amazement it finished off the setup and was working perfectly, so I'm guessing something has happened to my Mobo?
Anyone know what I can do/try to get this problem fixed?
I have a Gigabyte UD4 Revision 3 Mobo which I bought in April.
Would really appreciate some thoughts on this.
Thank you very much
