Can I bypass the video card on a iMac?

displays the same garbage? your video card is broken?

 

There is no way to bypass the internal video card and use another one.

 

you need a video card to display an image. Unless you can rig an external GPU to your iMac (not possible) You will get the same image. Your GPU is faulty.

 

you could try a USB -> DVI adapter
http://www.monoprice.com/products/subdepartment.asp?c_id=101&cp_id=10114&cs_id=1011403

The trick would be getting the drivers installed, and putting the displays in mirrored mode (or disabling the internal) - if screen sharing is on you could do it from another mac.

Performance will be pretty lousy though, since there's no decent acceleration and USB2 bandwidth is limited.

 

You cannot bypass the GPU for the internal monitor unfortunately.

How does that USB out work? Surely it's still using your graphics card?

Edit: Never mind. I see the USB devices are actually separate graphics cards, but connected via USB to the computer instead of PCIe. I've never bothered to look into this since it's so slow, but I guess it's better than not seeing a picture at all.

 

A graphics card doesn't only drive the connected monitor, but performs all the graphical rendering regardless of the output device. The OS graphical interface relies heavily on the graphic card and the graphic card memory buffers. Without a properly working graphics card the OS is likely not functioning properly either. So I would doubt you will get screening sharing to work either if it is a malfunctioning video card.

 

You could search for a used video card board for your model iMac and replace your broken one.

 

Sorry if I am being a bit of a noob, but doesn't every CPU come with a built in GPU on the CPU chip?

 

Not every CPU has an integrated GPU.

 

Pretty sure no CPU's had an integrated GPU in 2008 (which is what the poster has).

And even if the CPU does have one, the main board might not expose it. For example, it looks like the CPU in my iMac has a HD 3000 onboard, but only the ATI 6970 is hooked up to the ports...

 

Is the GPU removable like the newer iMacs? Maybe you could get a new one?

 

By garbage do you mean the image somtimes burns into the screen but not really the actual screen more so the GPU? I have the same iMac and same problem For example when browsing the web on a white webpage I can see my desktop icons through it, I've tested this many times and it never goes away. I'll be building a custom PC in a few weeks anyway no more problems for me!

 

By garbage he means it still displays Mac OS X. The only way to get rid of this is to install Windows onto the computer.

 

If the video card is bad, how would installing Windows help?

 

You're wasting your time on it.

 

Does your iMac work in Safe Mode?

T.

 

This is not entirely accurate in my recent experience. The 8600M died on my MBP. The MBP's display showed nothing and neither did connecting an external monitor. Apple Store confirmed the graphics card was dead. I was still able to screen share to the MBP and backup the HDD without a problem.

 

Problem solved