i have GTX 260 at 1.8Gb
and i want to buy a GTS 250 for physix,
how much power do i need for those? and where do i see how much my computer uses and the max ammount of power my power supply can give
What are your other specs ie: cpu, cooling, HDD's, mobo? Your best bet would to be to use an online power supply calculator. Just google for it.
Assuming you're not running anything to extreme I would say 600 to maybe 750 watts *shrug
If you look up the card it will give you the power requirements for your card.Myself I have a 1000 watt unit but i run the follwing setup.
Intel® Core™ i7 980x Extreme Six Core Processor (3.33GHz, 12MB Cache)
Dual 2GB GDDR5 ATI Radeon™ HD 5970 CrossfireX™ Enabled
12GB Triple Channel 1600MHz DDR3
600GB RAID 1+0 (4x 300GB SATA-II, 10k RPM, 16MB Cache HDDs)
Blu-ray Disc (BD) Burner (Writes to DVD/CD/BD) and DVD-ROM
Creative Sound Blaster X-Fi Titanium
lol your compensation is showing.