How do I make (WOL) Wake-On-Lan work ? I've tried everything now, all I see is green blinking power light when server is off. There is no additional options for "Wake On Lan" or power state. Any ideas ? Does this Dell PowerEdge 750 support WOL at all ?
WOL is based on motherboard and NIC compatibility. Both the motherboard and NIC have to support WOL capabilities. You'll also need an application or utility that has the capability of sending a WOL signal/packet.
Without knowing the BIOS version, I can't say for sure, but Dell's support website indicates it does (http://en.community.dell.com/support-forums/servers/f/1466/t/7612115.aspx). You'll need to reboot your system and boot into your BIOS to confirm.
After that, you'll need to boot the system into the OS and confirm the NIC's WOL capabilities are enabled. In Windows, it's an option under the device configuration; generally under Device Properties > Power Management > Wake On Lan.
Lastly, the application or utility you'll need to take advantage of WOL needs to capability to send a "magic packet". Some routers have this capability built in to a management page; you just need to configure the device as a WOL device. After it's configured, it's as simple as logging into the management interface and pushing a button.
There are also WOL apps available in all flavors online that you can run on your desktop or on your mobile device.
Check in the network card driver page (device management), often there is a flag there which enables WOL, and it's not the same as setting it in the BIOS.