It will work???

what is your graphics card model and what is the psu you have in the system.

list the system specs as well

GamerL: I have Intel Pentium 4 3.00 ghz 3.00 ghz
5gb ram
Abit al-8 motherboard
ati x1300 256mb I want to upgrade to Gigabyte radeon hd 6670 1gb drr3
1X HHD drive
2x dvd

PSU ALTIS A-380BX ATX Ver 2.2

That CPU is about 10 years old... The PSU should be enough to handle the 6670 but don't expect to see much improvements, you are going to be severely CPU bottlenecked.

if the CPU is actually 10 years old, does the motherboard even have a pci-e x16 slot? if not, it wont work at all.

id rather rebuild the entire system. a pentium 4 suggest that it is REALLY time for a upgrade

Yea pentium 4 3.0 came out in 2002. I don't think anything you add / upgrade on it will help you much... unless the upgrade is a new CPU + Motherboard + ram.

It may be possible, but I don't know that I would risk it unless you are willing to upgrade the PSU if necessary. I wouldn't bother upgrading both for an old P4 system.

My recommendation would be to step down to an HD 6570 DDR3. It has the same power requirements as your current card so it will work for sure, and it will still be a nice upgrade over the X1300. Also, I see no reason to get a card that will push your power requirements. The P4 and PCIe 1.0 will hold you back anyway.

Hopefully this will help out. Power requirements:
http://www.tomshardware.com/reviews/radeon-hd-6570-rade...
http://www.tomshardware.com/reviews/geforce-radeon-powe...

And Gigabyte geforce gt 630 1gb ddr3 will be good for my computer system.

id just get a new computer entirely. wouldnt even bother upgrading it