I installed 4gb ram 2*2gb...its showing 4gb ram but its not detecting graphic card..in device manager its showing error ..inte

Solution
The only thing I can think of is you having a terrible PSU that is struggling to cope and that additional few watts draw from your extra Ram is knocking the GPU below minimum required power. Otherwise I am stumped. Is your GPU fan spinning? If so, then yes you can try reinstalling Windows. If it doesn't spin when you first turn your PC on then it's a hardware problem.

genz

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The only thing I can think of is you having a terrible PSU that is struggling to cope and that additional few watts draw from your extra Ram is knocking the GPU below minimum required power. Otherwise I am stumped. Is your GPU fan spinning? If so, then yes you can try reinstalling Windows. If it doesn't spin when you first turn your PC on then it's a hardware problem.
 
Solution

genz

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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.