Adding a harddrive to existing system

is the drive already formatted and you want to access files that are already on it; if that is the case then hook it up along side the existing drive and go thought the user's manual and learn hoe to set the jumper on slave.

In the same since if you have a new drive it should be pre-formated or include software to do so. you hook it up like i told you before and set the jumper to slave.

relly this usually is a very strait forward thing and is almost like hooking up a flash drive to your machine (plug and play)

What format is the drive currently?
And which OS are you using?

I tired to hook it up to the system, and then it tried to boot off that drive rather than the drive that currently hold my operating system, and the os is Win 7 64 bit

When you buy a new hard disk it is usually not formatted. You said you hook it up and your computer tried to boot with the new hard disk instead of the hard disk which holds the windows 7 OS. Go to your computer BIOS (usually you press DEL key in your keyboard - please consult your motherboard manual for this). Try to find BOOT SEQUENCE or BOOT PRIORITY then choose the hard disk that holds your OS. If you don't know what particular hard disk it is then just choose different hard disk then hit F10 (save configuration) see if your computer boots on your hard disk with the windows 7 OS. After that, after it boots up with the hard disk, right click on Computer then click Manage here you can see your new hard disk, you can format it and use it.

The perfect answer that i was looking for, probably as you were writing i was updating the BIOs chose master, but there was no other
HD recognized so i think i have a big fat busted hard drive on my hands....

Do NOT get confused by the references to "Master" and "Slave" above!

There are jumpers to be set for Master or Slave ONLY on IDE (PATA) hard drives. If you have a SATA drive there is NO such setting. In fact, some SATA drives have jumpers on them for very different purposes and setting them wrong can make your drive temporarily appear dead when it is actually OK! So, if your new drive is a SATA unit and you moved any jumper on it, go to the manufacturer's website and find out how the jumper really should be set and fix that.

IF you have an IDE drive you are installing, the jumper DOES need to be set properly. If that's your situation, post back here and I'll tell you exactly how.

The source of confusion goes back over a decade. Long ago when only IDE drives were common, it also was common for the BIOS to assume that the drive that it must boot from (containing the OS installed) was the Master device on the Primary IDE port. But for more than a decade new BIOS's have a feature in which YOU set exactly which hard drive is the boot device. In fact, you actually set a sequence of devices to try. This is done in BIOS Setup in a place called the Boot Priority Sequence. Mine is set to try the floppy drive first (yes, I have one!), then one of my DVD burners, and finally one of my hard drives (the one that has my OS on it). If it fails to find a bootable disk in either of the first two devices, it simply falls though to the next, and only fails if ALL of the devices are not bootable. Most people today have only the optical drive and then one of their HDD's in the sequence.

Setting this is completely independent of setting up the parameters for each drive. Those are done first and separately. Then when the BIOS can use each drive device, those that are possible boot sources are available to choose when you get to setting the Boot Priority Sequence. In your case, just make sure that sequence does NOT include any attempt to boot from the new HDD you installed.

Great answer: A little bit more background on the HD it is from an external Harddrive Case and i am trying to access it from my computer to pull information off of it, Im not sure if the nature of an EHD is different than an HD but they look pretty damn similar. Information on the WD website is sparce, let me tell you what i am trying.

I Have put the External harddrive drive which i will call alien harddrive in the # 2 spot and the HD with the OS in the # 1 spot(they are both SATA) When i do The Alien hard drive comes to life after power on i get post and then it tries to load operating system from this drive.. Not fun So i shut it off then I disconnect the Alien hard drive and i boot right up with a quickness load from OS HD. I have even tried to connect it while the system is running, Kind of like plug and play. When i do that it doesnt turn on. So I looked into the BIOS While Both are connected and the BIOS doesn't even read The Original drive's existence..which is what lead me to believe that the alien has passed on. 1 more note, at this current juncture i only have 2 SATA cables so i had to disconnect my CD/DVD drive to test my alien HD.

That is the whole banana, Maybe you have some more advice/.?

The HDD units inside external drives are pretty much the same as any intended for internal mounting. That's why you can do what you are trying to do. Except, of course, it's not working so far.

Maybe a clue here: before you started this you had an optical drive connected plus your only Original HDD. Was the optical drive on SATA2? And now that is where your Alien drive is connected, right? Here's what may be happening: your BIOS is set in its Boot Priority Sequence to try the optical drive first, and then the HDD. BUT what it really is doing is: go to SATA2 first, then to SATA1. Well, with your 2-cable limit you have SATA2 now occupied by Alien Drive, instead of Optical Drive.

Do you have a third SATA port? Try connecting Alien Drive to SATA3, and leave SATA2 empty for now. When you power on, go into BIOS Setup right away and go to where the SATA ports are configured. Do four things:
1. Check that the SATA1 and SATA3 ports are Enabled. You might consider DISabling the SATA2 port for now since it has no device attached. If you do, plan to re-Enable it later when you re-connect your optical drive there.
2. Look at the SATA Port Mode for SATA1 (your Original drive). There are choices like IDE (or PATA) Emulation, AHCI, RAID, etc. Note whatever it is.
3. Now check the SATA Port Mode for SATA3 where the Alien Drive is. In some BIOS's you cannot set the several ports differently - there is one setting for all. So if that is you situation, leave it alone. BUT if you can set SATA3 port's Mode separately, make sure it is the same as SATA1 was.
4. Look elsewhere in your BIOS screens for the Boot Priority Sequence. Since you have no optical drive connected now, make sure it is not in the sequence. Make sure the Alien Drive also is NOT in the sequence. You should have ONLY the Original Drive in there.
Save and Exit, and let the system boot. It should boot from Original Drive. Once you're into Windows, you should be able to see Alien Drive in My Computer if it is working OK.

If you do NOT have a third SATA port to work with, the whole thing becomes a bit shorter. But the key thing is that Boot Priority Sequence. Make sure it uses ONLY the Original Drive, and does NOT try to use Alien Drive.

When you re-install the optical drive later, make sure to Enable its port, and to re-adjust the Boot Priority Sequence so it is back in there, along with Original Drive, but NOT Alien Drive.