Let say I got 3 HDDs, but my current PC only allows 2 HDD, 1 master and 1 slave, how to install the 3rd one, without using external casing?

Well..... I tried to put 13 eggs in a 12 egg carton. That didn't work either. Let me know if you find an answer, maybe I can do something with my egg problem.

Assuming your motherboard only has 1 IDE slot, and this is an IDE harddrive, you're out of luck, but I've heard of certain PCI cards that are reasonably priced that you can use as an extra IDE controller, but you'll probably need extra drivers for it.

Hope I helped!

yeah, i IDE slot can install 2 HDDs, with a branching cable.
i also heard that there is PCI card that can install more than 1 harddrives

Yeah, you can do all kind of things, but your post as in;
without using external casing?
seems to suggest you don't have room inside the computer for another drive. So... what are you looking for?

There are lots of PCI IDE controllers available.

Here is a listing from newegg: http://www.newegg.com/Product/Produc...&InnerCata=410 The Raid cards can usually be used in linux as IDE controllers, but you’re really wasting your money to buy one. Don’t expect their windows-software-raid to be easy to set up in linux.

My favorite PCI IDE controller is the Promise Ultra100 TX2 (or Promise Ultra133 TX2). Cheap and fast.

It supports up to 4 IDE drives on two independent channels and you can run at least two cards (some people claim 3 cards) in your system for a total of 8 (12) extra IDE drives.