effect of insufficient power to graphic cards?

It will slow down the card, the whole system and might overload the PSU and might fry the whole system with it. But your 450watts PSU is enough for your system. So I don't think you'll needing an aftermarket replacement.

if the card does not have enough power when you turn on your pc it will notify you that the card is underclocked to prevent damage to it.

psu's usually pop like chuck said too.

just stick your card in and try it.

99% of the time, if there isnt enough power, your system will just reboot.

Yo thanx buddy... so im not going to spend extra money to buy a new PSU, less worries... thanx for u guys' advice.

No the card shouldn't break...

But as with any power loss, you might lose data off the harddrives, if Windows for some reason is touching important data, like the registry.

Could be a small possibility of a surge to the system, if the PSU is really bad, but a few tests most likely won't hurt. and assuming that supply is OK, 400w is enough.

Since that PSU most likely doesn't have the special graphics card adapter, you should connect the adapter that comes with the graphic card, from two different lines, there's usually two separate coming from the psu, use both and you're safest possible..