If all that you are doing is replacing the hard-drive then you only need to do the following as the Dell cases are a screwless
design and only require you to:
- pop the case open,
- disconnect the drive and power cables, (noting these for reassembly later)
- push the green drive rail tabs inward toward the drive, and
- remove the drive from the case.
Next you'll need to replace the hard drive.
- Philips head screwdriver, or
- Nut driver.
- Take the old hard drive to a flat space, ideally a workbench and unscrew the four mounting screws from the drive rails.
- Take your new hard drive out of its Anti-Static bag and begin to put the drive rails back on the new drive.
- If this is the only drive in the PC I suggest you set the drive to being the Master drive on the IDE bus. If you do not know what this means google the drive model (on the label on the hard-drive) and you'll find details of how to set up the drive to be the master on the IDE bus.
When the above procedure is complete you'll need to re-insert the drive back into computer case. That is simply reversing the procedure you used to take it out of the case.
Finally you'll need to reboot the computer and go into the BIOS to ensure that the drive is being seen and is of the correct size.
Lastly you'll need to pop in the OS CD-ROM and rebuild the system.
Note that on some of the early GX150's there was a problem with the firmware of the CD-ROM that allowed you to load the OS, reboot and then the installation would hang as the OS could not read the hardware due to an incompatibility. This can be solved by simply replacing the GX150 CD-ROM with another CD-ROM during the build and then putting the old CD-ROM back in place after the final reboot of the PC before you log on for the first time.
Hope this is of some help from a newby solution provider.