I have h61m-d2-b3 motherboard which graphic card should i buy?

i have h61m-d2-b3 motherboard and 4 gb dynet and i5 processor ram but while im installing 4 gb ram my screen get fuzzy after 47 mins. but when i remove one of my ram it run properly. so i want to buy graphic car ir the range of 2000 ind rupees