How to change graphics card for thoshiba satelite c660 laptop

buy a new laptop, sorry, but the integrated graphics can not be replaced, nor can that laptop accept a new card

Most Laptops cant be upgraded your is running Intel on-board Graphics if I looked it up correctly. That means it has no Graphics card to upgrade and as such cant be upgraded.

Mactronix  

thank you for your advice but i further explore and i think my video card is ok.but the screen have problem because after i clone the display with other desktop screen it works fine. Is there any means rather than changing screen?
tedy  

It would seem that you do need to change the screen. your testing another display proves that there is nothing wrong with the hardware so nothing to fix.
You issue could be the screen or a connection to the screen, either way unless you are comfortable taking it apart yourself it looks like a job for a repair centre.

Mactronix  

unfortunately different problem same solution, or lack there of .

it's a real shame there has been no progress in this area in over 10 years. Very sad.