It's been 14 days now and you are still giving three word answers in rebuttal rather than moving on with life. Look at my best answer, buy a new PSU, or replace the motherboard/GPU and move on. You have barely £120 of hardware in total and something is obviously broken but you don't seem to want to tell us anything more than 'but it's this, but it's that.'
Why don't you actually run some tests of your own? Give some opinion. Lend it some thought. We are not paid customer services and I am not prepared to help people who seem thoroughly uninterested with helping themselves.
Are you able to get 4GB ram working? No. So 4GB RAM does not exist atm. Solution. Buy a new 2GB stick. Price? 2000INR
Done. Now GTFO.