Odd start up issue - must be hardware

Hello all

Since installing my new Radeon HD5750 graphics card, my start up time has gone crazy, and I'm wondering if I have a PSU or other hardware problem.

When I first started using this PC, after about 2-3 seconds of pressing the power button, I would get a "beep", the motherboard start up screen would appear, and then it would boot, nice and smooth, nice and quick. However since I changed the card from my old GT8800 to the new Radeon, it now take around 50 seconds to a minute after I press the power button before the motherboard even beeps and starts the boot process.

During the start up process, there is a loud grinding noise, which has been happening for months and months without causing any issue - it tends to stop if you tap the case, or after the boot up is complete, and I've put it down to a loose fan screw somewhere. This may or may not be relevant.

So the problem isn't a slow boot, it's the part of the start-up before the boot. Once it's up and running, I have no problems. Any ideas? Is this a PSU issue? I've bought a new PSU, but don't want to install it unless I'm certain. My current Arctic 600W should be more than ample for running my system. HD5750 card, one master HDD, one slave HDD, DVD RW drive, motherboard and nothing else - onboard sound, wireless card powered from motherboard.

I'm running Vista 64bit, Core 2 Quad 2.4 Ghz, 4GB RAM, Asus P5N-E SLI ACPI motherboard

Andy