Power consumption of 9500gt

how much power does a palit geforce 9500gt 1gb ddr2 require??
does a 512mb version of the same card will use the same amount of power or will consume less power.

i am going to use this for playing games at 800x600 with medium settings (or at the max around 1024x768).
so don't suggest any other card

i have a pc with config
PentiumD 820 (S) DC 2.8 GHz
800 MHz front side bus
motherboard name: Asterope2-GL8E
Chipset X200
2 GB DDR2 ram 667Mhz
Hard drive 160 GB SATA 7200 rpm
GeForce 7300LE 64 MB DDR memory
300W HIPRO smps with 19A on 12 V