PC won't recognize my HD.

May 4, 2009 7:14 AM

My computer is having problems with recognizing capacity of hard drives or recognizing the drives at all.

I have an old Dell desktop tower. It has a 1.8 Ghz processor and 384 MB of RAM. I use it mostly to store my music and surf the web, so it doesn't need to be top of the line. It has a 40GB drive, and a second hard drive my dad installed.

On Friday, I tried to replace the existing second HD with a 250GB drive. When I started up the unit after replacing drives, the computer wouldn't boot. It kept asking for a boot disk.

So, I swapped the original drive back in. As I was putting that drive back in, I noticed that it has a listed capacity of 120GB. However, when installed, the computer shows it as being a 40GB HD.

I'd like to have more storage on my computer. So, is there a way for me to get this PC to recognize the full capacity of the 120GB HD or to boot up with the 250GB HD?

posted by reenum to computers & internet (5 comments total)

Perhaps the hard drive has been partitioned? You can find this out by going to Computer Manager -> Disk Management.

If you want to boot from your new hard drive, you'll either have to install Windows on it fresh or duplicate the old drive to the new one. There are a variety of free tools to do this; I'm sure Lifehacker can provide guidance in this regard.
posted by sinfony at 7:22 AM on May 4

Your computer may not support drives larger than 136GB. Which was the previous limit under 28-bit LBA. You may be able to update the BIOS to support 48-bit LBA, but I wouldn't bet the house on it. More info on LBA
posted by borkencode at 7:26 AM on May 4

When you installed the new second hard drive, you might have messed up the jumpers on the drives. If it was installed on the same cable as the 40gb hard drive, you need to make sure its jumper is set to slave. (Usually, this means removing the jumper completely.) If it wasn't set right (both the existing 40gb drive and the new drive were set for master), the PC won't recognize either one, and fail to boot.

Windows XP (after service pack 1 or 2, I for get which) doesn't care about the LBA problem. As long as the BIOS recognizes it at all, the OS will see all of it. With one very important exception: you cannot have the boot partition be larger than the 136gb barrier. IF you are installing a large drive like this as the boot drive, you need to partition it so that the C: partition is smaller than 136gb. Then all will go fine. (What happens if you don't is that it will work fine for a while, until windows updates some important file, and places that file near the end of the drive, beyond the 136gb barrier. If Windows needs this file during the boot process and can't see it because it hasn't loaded its 48bit LBA driver yet, you will get a blue screen.)

When you say "the computer shows it as being a 40GB HD", is that in the BIOS, or in the operating system? What size does windows say it is? If windows believes it's the right size, you are fine.

So, check your jumpers and the drive should work fine. A BIOS update couldn't hurt, however. As long as you don't lose power during the update...
posted by gjc at 7:41 AM on May 4

gjc's got some good advice here--I'd definitely start with the jumpers. I've had countless problems with that (where a drive set to slave was hooked up as a master or vice versa and it either didn't detect the drive or, if it did, had the wrong size), and the "Cable Select" option hasn't always been reliable.
posted by jgunsch at 8:20 AM on May 4

Yes, cable select can be troublesome. It only works on cables that have a certain wire clipped for the end device. So if it's a normal cable, it won't work. Conversely, some ancient Compaqs wouldn't let anything except CS work.
posted by gjc at 4:34 PM on May 4