|Here's how I got it solved:|
removed DVD drive, HDD, WiFi adapter, RAM module.
Started up, screen obviously remained blank.
Shutdown, RAM in, start.
Now it displayed attempting to use LAN adapter for booting, with no success.
Restarted, entered BIOS, disabled network boot.
Shot down, inserted HDD.
Success - booted straight into Windows!
Shutdown, inserted WiFi adapter. Success again.
Shutdown, inserted DVD drive. Success, no errors.
What I think it was is that BIOS got confused after old HDD was replaced (it's hard to tell because particular BIOS does not show just much) and remained to poll LAN adapter as boot priority on background somehow.
Anyway, by removing and reinserting devices as above I was able to find what looked like a cause of conflict. Whether the trick lies in disabling network boot or reinserting devices in certain order...don't mind to try again until facing the same problem again, honestly...