shairu :
i couldnt find board with 775 socket together with the I5 socket so i bought new intel I5 2500K cpu with new asus board.
the ddr3 are not expensive but i have no another question, do i need much better power suply if i have a basic 500w now?
does the i5 cpu needs that?
If you do not use a discrete graphics card, a psu of 300w is sufficient, assuming a normal complement of drives, fans, etc.
It is the add on graphics card/s that create the need for more power.
Here is what EVGA recommends for their graphics cards:
GTX550ti needs 400w with 24a on the 12v rails plus one 6-pin PCI-E power lead.
GTX560 needs 450w with 24a on the 12v rails plus two 6-pin PCI-E power leads.
GTX560Ti needs 500w with 30a on the 12v rails plus two 6-pin PCI-E power leads.
GTX570 needs 550w with 38a on the 12v rails plus two 6-pin PCI-E power leads.
GTX580 needs 600w with 42a on the 12v rails plus one 6-pin and one 8-pin PCI-E power lead.
GTX590 needs 700w with 50a on the 12v rails plus two 8-pin PCI-E power leads or 4 6-pin power leads.