[jibijaba]

Hi,

I have a PowerPC G4 800 Mhz, 2MB L3 cache and 768 MB SDRAM. I use OS X 10.3.9.

I've been having issues recently with my Logitech Mx310 optical mouse freezing intermittently as I work. The only way to fix it is to unplug the USB from the USB hub I'm using and plug it back in. (This also happens when I'm plugged directly into the USB port on the computer, so I don't think it's the hub).

Also, I've noticed that I'm sometimes unable to plug in USB devices because it says they require too much power, i.e. I get the warning that there is too little power for the USB device.

About the same time that this has been happening, a few other issues have emerged. For one, I occasionally get the "Black Screen of Death," i.e. when the screen dims and I'm told to restart my computer. (This is obviously the most disconcerting problem!)

So my questions to the forum are:

-- Any thoughts on what might be causing all of this? Do USB ports ever "go bad" or lose their ability to deliver power or send/receive data? If so, can you easily switch out the USB port on a G4? And is it possible any of this is related to RAM or something else?

-- What in general causes the "Black Screen of Death" and how can it be stopped?

THANKS!

J

[imitchellg5]

I know that when my uncle upgraded his PowerMac G4 Quicksilver 867 from Jaguar to Tiger, his PCI usb hub slowly died.

[merp]

The "Black Screen" is what a kernel panic looks like in OSX. You've 3 RAM sockets filled, right? With the sudden "low power" messages, I'd suspect the power supply the most. Dips in the voltage will cause no end of weird, intermittent problems in a computer. You're lucky it's actually giving you the full KP screen; at least it's more likely to have halted the filesystem before going down.

You can try this to troubleshoot it. Put a multimeter across some of the power leads to the disks and motherboard, and check their readings under load against the specs on the side of the PS. I bet they dip appreciably right when it crashes, and there's your evidence.

[kick52]

your mac/os might not like the hub that you are using.

try using your mouse directly pluged into the back of the computer. if you get no kernal panics, your hub is bad. and also, your mouse may be faulty. try using your mac with another mouse that you know works.

[jibijaba]

Thanks for the help!

[reader50]

The power supply is not causing low-power messages. Too little power from the power supply does not cause an error message to appear, it causes the computer to crash or shut down. The low-power messages are coming from the USB system.

A USB channel can supply a maximum of 500 mA of current. No single USB device is allowed to use more than that or the USB port will shut down until you unplug-replug into it. Things get more complicated if you are using a hub.

If you are using an unpowered hub, then all power still comes from the one real USB port the hub is plugged into. With multiple devices plugged into the one port, things will still be ok if all the devices are low-power devices. In other words, they still add up to less than 500 mA total. Note: the hub itself usually draws a little bit too, especially if it has some neat indicator lights on it.

If you have a powered hub, then the hub draws little or no power from the computer's USB port. Instead, the hub supplies up to 500 mA to each of it's outgoing ports, and shuts down an outgoing port if it draws too much.

I'm guessing that you are using an unpowered hub, and that the number of devices plugged in adds up very close to the 500 mA limit.

Finally, your MX310 mouse has gone bad. Specifically, some wires in the cord have been flexed too much and have broken enough to intermittently disconnect. While it is possible to put a new USB cord on a mouse, it isn't worth the time unless you have a strong emotional attachment to that particular mouse. Toss the mouse and get a new one. This may be causing the kernel panics too - the USB system doesn't expect devices to have one wire disconnect now and then.

You can find out more about a kernel panic by checking the logfile. It's located in /Library/Logs/panic.log