I know it is something related to the graphical side, but the thing is, it actually sometimes boots in either the first or second PCI-E X16 slot. And that is to say once in every 5 or so attempts. But when it's in the 3rd slot, which is 8X, it boots up straight away and even after shutting it down it boots up normally. So it seems like a motherboard issue moreover than a graphics card issue.