Ok, so after a lot of research I have reached a dead-end.
I'm having problems installing Win 2008 R2 64x OS on a Dell PowerEdge T110 II server with PERC S100 controller.
I've created a RAID1 configuration using 2 hard disks, In the Perc s100 management it is visible and the status is ready.
The problem occurs when I try to instal OS, i cannot see the drives, loading drivers from USB doesn't help either. I tried 12+ different drivers including (http://www.dell.com/support/home/us/en/19/Drivers/DriversDetails?DriverId=W3N37&FileId=2942618202&DriverName=Dell%20PERC%20S300%20Adapter%2C%20PERC%20S300%20Integrated%20Modular%2C%20PERC%20S100%20Integrated%2C%20RMSD_PERC%20S100%20Integrated%2C%20v.2.0.0.0162%2C%20A05&productCode=poweredge-t110-2&urlProductCode=False) and still i get the message "No signed drivers were found".
Now in the Dell BIOS (v2.7.0) menu, in the Integrated Devices menu, there is no embedded Perc s100/Raid line, could that be the problem? Although there is SATA settings next to Integrated devices, where embedded SATA...[RAID] is selected.
Any suggestions for me to try out are welcome.
EDIT: Trying different USB's and formats for drivers to be read.
SOLVED: Set Boot Mode to [UEFI] boot OS from CD/DVD, prepare USB for controller driver DELL_MULTI-DEVICE_A05_R294488.exe (You need to extract the .exe to a folder). Now it finds the the driver during the OS setup.