The psu is a low end one with 250-350 watts and my budget for. Gpu is like $100 or less than $140.
For that price range I suggest two alternatives
1: ASUS HD7790-DC2OC-1GD5 Radeon HD 7790 1GB 128-bit GDDR5 PCI Express 3.0 HDCP Ready CrossFireX Support Video Card
2: PowerColor AX7790 1GBD5-DHV2/OC Radeon HD 7790 1GB 128-bit GDDR5 PCI Express 3.0 HDCP Ready CrossFireX Support Video Card
both gpus have up to 150W Power Consumption, is your psu a certified psu!?