Having read through the other posts I would have to say, as previously mentioned, that the problem is almost certainly your PSU.
The POST Beeps seem to show an error with the GPU but this could be indicating a lack of power rather than a "fault". It doesn't matter if you are using a CRT or LCD monitor, they do not draw power from the Graphics Card, they have their own power source so you can safely ignore that piece of advice. The problem is that, during the BOOT process, there probably isn't enough steady power flow to the GPU and a more powerful PSU will provide that.
The manual for your Motherboard recommends a PSU of at least 500 Watts so you are already underpowered according to Gigabyte. Also checking the specs for your choice of Graphics card the power requirement is a steady 86 watts. From these figures you are almost most certainly underpowered.
Hope this clarifies the issue a little bit further for you.
