Gigadesigns MC7447 and G4 CUBE

[indibil]

Hi, some friends and I have been testing upgrades with their G4 Cubes. I think I remember reading in some thread that some processor upgrades aren't compatible with VRM Upgrades, but I can't find it. We're testing with an ARTMIX VRM.

The Cube has the MC7447 patcher applied.
I have a Gigadesigns MC7447 processor at 1.6GHz, for G4 towers, not for the Cube, and to make it fit inside, I replaced the solid-state capacitors with LowESR tantalum capacitors, with the same final capacitance, and I adapted a copper plate to fit the Cube's heatsink. It's running at 1.6GHz at 1.3V. This processor, both with its original heatsink and with this copper plate, works perfectly in a G4 GE and a G4 DA after modifications. But it doesn't seem to work in the Cube.



It occasionally boots, but after a while it freezes. Most of the time, when I press the power button, the power LED lights up and then turns off, like when there's no processor, but the two motherboard LEDs are lit, DS1 green and DS2 red. And the three ARTMIX LEDs are lit, but it doesn't work. I put the original processor back in, and it works fine.

Has anyone adapted one of these Gigadesigns to a Cube and had it work? Am I doing something wrong?

 

[willmurray461]

If it works perfectly in other computers, it's probably overheating due to the cube's poor airflow. I'd try setting the jumpers for the lowest possible clock speed and seeing if it still locks up.

 

[ObeyDaleks]

Have you tried using a different PSU? The Artmix VRM should be able to handle this. Heck, even the stock PSU should probably work (until it fries and takes half the cube with it). But the symptoms you describe definitely hint at a power delivery issue.

 

[indibil]

Have you tried using a different PSU? The Artmix VRM should be able to handle this. Heck, even the stock PSU should probably work (until it fries and takes half the cube with it). But the symptoms you describe definitely hint at a power delivery issue.

Yes, perhaps when turning on this processor model, it produces a voltage drop sufficient to knock out the device. I have photos of a Gigadesigns for Cube with an MC7457 that has lower-capacity capacitors (4 x 150uF) on the 5V input. Perhaps if I remove the capacitors from the input, it could start up? Adding capacitors might be worse.

 

[willmurray461]

Yes, perhaps when turning on this processor model, it produces a voltage drop sufficient to knock out the device.

That could explain why it doesn't start up, but it wouldn't explain why it would lock up after a while. Nevertheless, if you have an oscilloscope and probe, you could test this theory.

 

[kjay]

I know the patchers are specific to manufacturer of the card. I accidentally installed Powerlogix patcher for a NewerTech cpu card in a QS and had all sorts of boot issues. I'm assuming you're using the Giga patchers since you have the cards working in your towers?