System boot up failure after adding another HDD

[Estorm732]

Hello.
Today I bought a new 2TB HDD to add on my current system with a 500GB one.

As far as I know,what I had to do was to plug the new HDD with a power and sata cable,and I was good to go.So I plugged the SATA cable,had to use the same power cable I was using for the old HDD (it had 3 outlets on it and no more cable ports on power supply,so I just plugged another end to the new HDD),and pushed the power button.

And nothing happened.It was as if there was no power,let alone the system booting up.

So I removed the cables from the new HDD.Tried again,the system started but now it's asking me to select proper boot device and reboot,and the only boot device it seems to acknowledge is the DVD-Rom.

Why has such a thing happened and what am I supposed to do?
I'd really appreciate some help.

Thanks.

EDIT: Oh and my motherboard is P7P55DE-Deluxe in case it's needed...Quite an old model I suppose.

 

[Estorm732]

Situation update:

I got the system starting now.Looks like I had mixed the old ports of the DVD rom and the old HDD.Exchanging those has got the system running.I also got it running with the new HDD plugged,however I cannot see it on My Computer.

The system found the new HDD on bootup,and even did an automatic driver install on Windows startup,but it's nowhere to be found now =/

Still in need of some help about the matter.