Problem With Booting

[Desertfox89]

So I discovered that one of my 2 HDDs was on the verge of death (running really slow and making a ruckus), so i opened up my build and unplugged it and took it out. However after I did and tried to start my computer, the strangest thing started happening. My Radeon 4870 started blinking 3 red lights on its back and making a noise every time the lights lit up. The lights lit up in conjunction with my cd drive light which would light up at the same time as the Vid Card lights.

I am suspecting that the PSU might be the problem (OCZ ModXStream Pro 700W Modular Power Supply). Anyone got any advice or should i just order a new PSU?

This is quite strange!