Well if you have run all of those then the only thing really left is your motherboard. There is no test that check if a motherboard is bad. So you'll have try out a new one and see if your problem persists.
Are you sure that the PSU is powerful enough? Use a online power calculator and see if your power consumption is over the 450W you have. I thin it is. I think the PSU is underpowered and that is the issue.
Are you sure that the PSU is powerful enough? Use a online power calculator and see if your power consumption is over the 450W you have. I thin it is. I think the PSU is underpowered and that is the issue.