That would explain why the Sonnet card doesn't ever crash the computer, but the ATI card always does under load.They tend to have onboard regulators and I'd expect that to be fed from 5V. 5V had much more capacity than 3.3V on beige macs.
Its just a thought at the moment, it might not be the issue - can you connect some wires to the 3.3v and ground, run them outside the case and monitor it while under load with a multi meter? See if it dips? If it does, a higher power regulator might be needed. But I happen to have a 6500 PSU on the floor in front of me and the 3.3V is 10A!That would explain why the Sonnet card doesn't ever crash the computer, but the ATI card always does under load.
I was wondering if anyone could link a better/more suitable 3.3v regulator for me to replace the current one with? I'm not good with electronics...
In addition to the stock PSU my CC also has a Mean Well EPS-45-5 installed (40W, 5V, 8A). Is that not sufficient? I've noticed that when the logic board is fully populated with a G3 card, max RAM, an ethernet card and a GPU, the CRT seems to sort of struggle to turn on. It takes like 10-15 seconds for the CRT to finally light up and I can hear the high voltage engage one or two times before it finally succeeds. This doesn't happen with another, weaker logic board installed.Like I said, 1A isn't much for 3.3v. The crashes under load are a tell tale symptom. I would be pretty surprised if a beefier regulator or different PSU didn't sort it.
You'd need to common the grounds between the two supplies, but otherwise you could power the computer lile that.I'd like to verify the 3.3v situation; would it be possible to temporarily hook up a desktop ATX power supply to just the logic board, leaving only the CRT powered by the stock PSU? I'd turn the ATX power supply on, then the stock one inside the CC, and then pressing the power button on the keyboard should be all I need to do to turn the computer on, right?
Would any of this work?
Yes, the new PSU is mounted directly to the metal shield of the old one via some metal stalks. I can common the grounds between an ATX PSU and this one just with an alligator clip, right? Is there an optimal place to source the ground on the ATX PSU or can I just get it from a ground pin?You'd need to common the grounds between the two supplies, but otherwise you could power the computer lile that.
Do you know the ratings of the built in powersupply and your current auxiliary power supply? You have commoned the grounds between them haven't you?
Thank you for your response, Byrd. I do already point a desk fan at the internals of my CC, but that brings up another point: one of these days I'd like to install a fan of some kind inside my CC in addition to the PSU fan already present to help cool the fully decked logic board. Does anyone have any experience with this?Lastly, point a desk fan at the internals with "the works" installed to rule out overheating, does your CC have an additional fan installed on the side of the case? A common mod was to cut away at some of the shielding and plastic internal skeleton to install a relatively high speed 80 or 90mm fan inside. With G3 + GPU it will overheat using the stock fan.
Any comments or advice?
Unfortunately I've already tried it. It should still work though, right? I don't see how anything could have been damaged.Do not power the machine up with the analog board disconnected from the PSU. They are dependent on one another. I have done this, do not do it.
I'm not sure if that was actually your plan but I wanted to put that out there just in case.
Unfortunately I've already tried it. It should still work though, right? I don't see how anything could have been damaged.