If your PC has an expansion slot for a 3.5" hard drive I'd buy a new 1.0 TB drive (a WD #
WD10PURZ made for surveillance) on
amazon for $57.
You power supply will likely have a SATA power connector but you'll need a SATA data cable from the drive to the motherboard. Put that in your BI server PC, format and set up as 'D' drive.
If you have never done something like this I suggest you get help from someone qualified. It's really not that difficult but there are procedures for working inside a PC to prevent static damage, especially with the drier air of cooler weather now that provides the best conditions for damage from static electricity.
Create a folder on the new D drive named '
Blue Iris' and inside that folder create 2 more folders named 'New' and 'Storage'.
In BI, go to 'Settings', then 'Clips & Archiving', under 'Folders' click on 'New', over to the right click on the browse box with the 3 dots and locate your desired folder on D drive ( path would be "d:\Blue Iris\New') then click on 'OK'.
Do the same to redirect writing to 'Storage' from C drive to the new D drive.
I would disable recording to the DVR's drive and use only Blue Iris but that's your call. I have set several up both ways. You may consider leaving the DVR recording until you are satisfied with how BI is recording (motion, alerts, schedule, etc.) then disable the DVR's recording.
Lastly, you could use an external USB drive if your PC has no room but they are notorious for disconnecting, etc. If at all possible go with the internal drive I suggested or a larger one if desired.