Better eyeglasses, perhaps? ;D
Try using another monitor if you have access to one. An almost similar situation happened with me when I was trying to configure my Apple MS 17" to my mom's (now deceased) HP Pavilion. When I went over the 1024 x 768 resolution setting on the Windows control panel, the monitor blacked out, and I was unable to reset it. As a result, I used another properly configured monitor to return the control settings back to normal in order for the Apple monitor to work again.
I doubt that your video card went on the blink, but I would open up your IIfx just to check anyway for faulty caps, or any unusual appearances. Dust can also be a major contributing factor. Check the cards' contacts as well. Missing contacts could also result in the monitor blacking out.