Windows 7: External USB drive not being seen when connected to motherboard

Hi, I have a problem. I am using an external USB combo drive, now i decided to take out the drives and have them permanently plugged inside my system through sata. None of the hard drives are seen in the bios or windows 7 x64 yet when i plug them into my usb combo external they show straight away. I know it cant be a setting as I already have a couple of sata drives internally that work fine. Why are these two drives that have been sat in a usb external not being seen at all when plugged internally on the motherboard?

I hope that you had connected both the power cables and SATA cables to your drives and checked that are plugged securely.

That apart, if your computer is quite old it most likely caters to only 1,5GB/sec SATA drives - in other words your motherboard may only have 1.5GB SATA Controllers. If you are connecting 3GB SATA drives, you may have to jumper it to 1.5 GB for these to be recognised. Just check on this.

It is a Sata 2 board Biostar G41d3c and yes the cables are all working and plugged in correctly