Have you looked to see if the fan is moving on the video card? The problem your describing has happen to me way to many times and it always involves a new card.
How much money can you afford to spend? Your 700w power supply can handle any cards out so long as it has the connectors, thou most cards come with adapters if needed.
How much money can you afford to spend? Your 700w power supply can handle any cards out so long as it has the connectors, thou most cards come with adapters if needed.