What do you mean connect wire to graphics card?
A) Computer is to be OFF when connecting a monitor cable.
B) Computer is to be OFF, and unplugged from power; when plugging the power cable from Power Supply, into it.
You are also supposed to be Following Anti-Static Precautions.
What Power Supply are you using?
Manufacturer name, and model number. Post back in a Comment.
Motherboard requires about 150 Watts by itself.
That isn't including what the Processor (CPU) needs, Ram Memory needs, optical drive/s need, computer case fans need; AND what the Nvidia GeForce GTX 260 graphics card needs.
It needs 225 Watts by itself.
(Manufacturers usually state around 500 Watts MINIMUM.
This is in reality based on a COMPLETE computer system, and NOT just the graphics card itself)
What do I base that the GTX 260 needs 225 Watts?
(I see that as the -> Maximum, though )
A PCI Express x16 expansion slot on a motherboard, is only capable of 75 Watts of power.
That is why the additional power cables were brought out.
The 6-pin PCI Express power cable that plugs into the GTX 260, is capable of an additional 75 Watts of power.
The Nvidia GeForce GTX 260 requires using TWO 6-pin PCI Express power cables
That means 150 Watts of additional power.
75 Watts + 150 Watts = 225 Wattshttp://www.geforce.com/hardware/desktop-gpus/geforce-gtx-260/specifications
"Supplementary Power Connectors -> 6-pin x2
If you are using just one 6-pin PCI Express power cable, '
this = NO.
NOT enough power for the graphics card.
What will happen?
A) The PCI Express x16 slot connector oins, will burn
B) The gold plated contact pins on the bottom of the graphics card, will burn.
C) The connector on the graphics card, that the 6-pin PCI Express power cable plugs into, will burn.
D) The connector on the 6-pin PCI Express power cable will burn.
The graphics card will burn up.
Too little power.
IF, your Power Supply has enough power, and IF there are two 4-pin Peripheral power cables that aren't being used; you can use a 6-pin PCI Express power adapter cable.
Example of 4-pin Peripheral power cable,http://www.playtool.com/pages/psuconnectors/connectors.html#peripheral
Example of 6-pin PCI Express power adapter cable, was shown in the Playtool link,http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpresshttp://www.directron.com/pci03.html
(Connectors are white, and hard to see against white backdrop. You can enlarge all 3 views)
For additional questions please post in a Comment