Switching graphics card -> boot but no picture.

Hi,

Maybe this is very simple but I simply cannot understand it.

Anyway, here is the issue I have.

I have a quite old PowerMac G4 AGP for my kids. It runs latest Tiger. It has an really old ATI Rage card in it and playing flash games is really slow on this one (compared to my iMac G5).

Now I though that if I replace the ATI with something quicker it would make a difference. I got a Geforce 2 MX card (MAC version with ADC and VGA connector) and plugged it in. No picture. However it booted OK. At least as much as you can tell from the startup sound and the rattling harddisk.

I but back the ATI card. To my surprise - NO PICTURE as well!!! What did I do wrong? It still seemd to boot but the monitor didn't show any signal. Tested another VGA monitor. No difference.

I then tried Alt-Command-P-R whil starting up -> didn't work
Pressing the little switch (CUDA?) on the mother board -> no difference..
Trying to boot from Tiger Install disks -> Still no picture, boot booting..

Then I tried all sorts of things. Removing the battery. Remove ATI card at put it back. Let it stay with power cord disconnected for half an our.

The suddenly it worked... I don' know exatcly what I did to get it to work. Unfortunately.

Still I haven't solved the original problem with slow graphics so I tried to flash an old Geforce 5200 board I had laying around with an supposedly approriate MAC BIOS and tried that one. Exacly the same happend as I decribed above. Eventualy I got it back working again.

It has to be a simpler way! It has to be something fundamenatlly wrong I am doing. Is it possible to anlalyze this in some log files? Since it is booting, is it possible to remote diagnose it from my other MAC. How do I enable SSH login on it? What should I look for? My theory is that somehow the configuration inside the NVRAM (or wherever it is stored) is screwed and tells the computer to output the signal on some non existant DVI / ADC connector. (I don't have an DVI / ADC screen to test with)

Please help!

/Mattis