I wonder if anyone can give me some advice about a problem with a Gigadesigns card. I have two known good cards from Giga (the 1.467 GHz model using the XRC7455pf1400 chip). Both cards work perfectly in a G4 450 SawTooth running at 1.4 GHz.
But when I reset the card jumpers for the 133 MHz bus and put either card in my Digital Audio G4 733 (pre-Quicksilver), I immediately get a VERY LOUD truncated boot chime and then refusal to boot with no video or mouse, etc. The power key, forced restart button and programmer’s button on the front panel are all dead too. The only way to restart is unplug the cord.
I have checked the boot ROM and it is 4.2.8f1 as recommended by Giga. If I try to restart into open firmware using CO +O+F, I get nothing at all--just the LOUD boot chime. If I restart with the stock 733 card, the machine is completely normal with no KPs (running 10.2.6). I have run reset-all, reset-pr and reset-nram from open firmware with the stock 733 card but the same problem occurs as soon as the 1.4 GHz card is installed again.
I have tested the 733 RAM (PC133) in another G4 450 machine and it runs fine with the Giga 1.4 GHz cards in that machine and I have swapped out the hard disk, CR-RW, nVidia video card and all seem normal. We have used the CUDA switch, taken out the PRAM battery for 2 hours. We have replaced the video card, tested the PS voltages and all seem normal.
I have spent hours on the phone with Giga but nothing we can do will make these cards boot normally in my 733 DA machine. Once or twice, we have managed to get the cards to the gray Apple splash screen by increasing the core voltage to 1.75 V (1.60 V is recommended) and downclocking to 1 GHz but as soon the gray Apple ‘clock’ starts, there is a KP. This happens every time.
Does anyone know what might be causing the LOUD truncated boot chime as soon as the Mac is booted with the 1.4 GHz card installed? It seems as if the main board chokes at that point (the first DMA perhaps) and never proceeds to subsequent I/O. Giga swears they have customers using this card in this model of Mac. I have run the hardware CD and nothing shows up as abnormal. With the stock 733 card, the Mac behaves perfectly.
I wonder if there is a bug in the open firmware that shows itself with this model of Mac and CPU and OF 4.2.8f1? Is there a way to force a new install of the 4.2.8f1 firmware? I have tried to downgrade to 4.1.9 but it is not possible and I have tried to reinstall 4.2.8f1 but it just tells me 4.2.8f1 is already installed.
Any ideas would be most welcome.
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