"430watt power supply"
Is that a no name PSU? If very generic, you'll find I always reply get a namebrand PSU to best handle power needs. Even though you got a higher wattage PSU, alot depends on the stable and dependable delivery of power output and once you get a hi-powered video card, it really tasks the PSU. Plus, understand during boot-up alot of power is required by all devices as this is the only time it will do that, after such, it drops down abit. This is also a time I mention when if things get freaky or weird, expect a problem to crop-up. I suggest you get a namebrand PSU and then continue from that time on. Last note, newer video cards come with s/w pgms. that in itself is a big load for start-up and maybe a slowdown cause, however see if you can disable it during start-up as in many cases once the setting are selected, you don't need that vendor pgm. no more. I said, disable, not delete or remove. check the start-up section under [msconfig], try start->run->type: msconfig and find startup, disable(uncheck, 1 at a time), save, reboot and check results.
ever since I installed a new graphics card my computer will sometimes hang on startup. just after the windows xp loading screen, the computer goes dead - but it only happens sometimes, the rest of the time it starts normally, though it takes longer than it used to.
pentium D 820 2.8ghtz processor
430watt power supply
before upgrade, I had a 350 watt power supply and was using ATI Xpress200 integrated graphics
I thought perhaps the power supply was inadequate, but some sites seem to list the minimum as 400watts, while the box specifies 450