I have bought Radeon 9800 (not SE, PRO or XT... just 9800). I put it into AGP and there is no signal from monitor. CPU, CD/DVD drives start but monitor is black and there is orange light on. My config: MSI KT3 Ultra 2 and
Codagen 300W. Where is the problem?

Suggestion

Double check to see if the power supply is connected to the graphics card itself. I think the RADEON 9800 requires its own power supply line to it. If there is, that should be the problem.

But it is connected...

Other possibilities

Hmm...the graphics card is in the AGP correctly and the power supply is connected to it? Try double checking if your monitor is connected to the graphics card, and double check the mother board to see if the 20-pin connector is connected from the power supply and the motherboard correctly and if your motherboard has a 4-pin connector, make sure it is connected with the power supply as well. Because I've been in the simular situation before and I've had the same results as you had and the only problem was that I forgot to plug in the 4-pin connector and thus it solved my problem. Also check if you have an LCD monitor that the mode setting on the back is set to Digital instead of Analog if you have the monitor plugged into the DVI port of the graphics card and that if you don't have an LCD monitor, make sure its setting is set to Analog and that the monitor has a VGA-DVI converter and is plugged into the VGA port of the graphics card. If I this sounds too confusing, I recommend reading the troubleshooting portion of the ATi RADEON 9800's User Manual if you haven't already.