May be you need to update the firmware of the server, also make sure the Server supports the higher capacity harddisks which you bought from Dell website.
In these kind of cases normally firmware will solve the problems.
First, is you really have to determine if the hard disk drive you bought is compatible with your computer system. Remember that there are 2 types of hard disk drive when it comes to compatibility, these are the SATA and PATA hard disk drive. Another thing is the Master and Slave settings of the hard disk drive, you can set the master as the primary hard disk drive and slave as the secondary drive.
There are only 2 possible problems with your computer system. These are the following.
1. Master and Slave Settings – There might be possible settings needed for your hard disk drive to work and these are mostly on master and slave settings. Your master settings should be for your primary hard disk drive and the slave for the other drive.
2. Hard Disk Drive Types – There 2 types of hard disk drive, these are the SATA and PATA. You have to make sure that these have the same types for you to work.