PC wont boot when i run my palit 4850 sonic card

hi there
my pc config is
Phenom II 940
Asus M3N78 EM
2 X 2 DDR2 800
2 X SATA HDD
Palit 4850 sonic
Tagan TG500 U37 PSU

my prob is that when i try to run my pc with my palit 4850 sonic gfx card...my pc wont boot...some people suggested me it could be due to psu so i even got a new tagan tg 500 u 37 psu but still the problem persists
my pc boots perfectly well when i run on onboard gfx
prob come only when i try to run the gfx card on my mb...most of the times it doenst boots
can any one please help me determining what the real prob could be

In the bios, change to video order for PCI-E first.

It may still be on onboard, ignoring the PCI-E VGA.

Brad

welll....i have run my gfx without any prob for almost 10 days.....this problem occoured recently.....and as far as i remembed....prefrence was set to PCI-E in bios

Is your on-board video set to AUTO?
If it is set to auto just go and change the setting to disabled... I am not sure but it might make a difference.
In my BIOS I have it disabled.

Hmm it sound more like hardware conflict issue.

There are two thing you can try out.

1. Reset the BIOS to its default settings, than go to BIOS set priority to PCI-E and try booting like that.

2. Remove 4850 from mother board and power up the PC without the card in it, let the BIOS refresh and then power down the PC, insert the card back in and power up again.

The BIOS manages the IRQ assignment for any additional hardware you add, sometimes conflicts occur that can cause additional problems, like not being able to boot, or not receiving sound output, etc.