I have an HP DL380 G5 server and I was wondering if can I put in standard notebook 2.5" SATA drives?
In the front where the drives go, the SATA connections dont seem to fit.
Yes, you can. (It's tacky, but it will work)
But if you choose to move forward...
You'll need to place the drive in an HP drive carrier/caddy/tray. This is what secures the disk in the hard drive bay and provides hotplug connections to power and the SATA/SAS connection. This interfaces with the SAS SFF-8482 connector on the DL380 G5's drive backplane.
As ewwhite points out they'll physically fit into the servers with the correct disk caddies but you don't have to look far online to read the tales of woe that people run into when using non-HP disks with HP controllers as HP-branded disks have specific firmware on them that extend the functionality, reliability and in some cases performance of their disks. I just want you to be aware of this.