Is it Safe to run the computer 24hrs a day?

[nxtnctno]

if you sleep where the computer is located, you shouldnt leave it on. it causes cancer and messes up your brain because of all the electricity and radiation

 

[Swapmaster]

You don't wear tin foil hats do you?

 

[shackrock]

I hate SUV's too...and that's just the beginning. ha

but still, think about if that power from the overnight computer was in some 3rd world country, they'd have lights.

 

[dgatwood]

Do PC's really "hibernate?" My Mac just sleeps! Anyway, I generally keep the sleep function off. I've read user reports suggesting that certain external devices (especially Firewire) are not recognized when exiting sleep mode. I use a MOTU 828 firewire interface and it tends to be picky about startup procedures. So, for this Mac user, no sleep.

That -should- be wrong.... Firewire devices should always be recognized after waking from sleep, barring bugs. Now if you had said USB devices, I wouldn't be at all surprised. USB provides no GUID guarantees, and thus they can be more of a crapshoot under certain circumstances (e.g. distinguishing between two USB devices of the same brand that don't happen to have a hardware serial number). But I digress.

Anyway, the point is that if your firewire interface doesn't show up after sleep, make sure you're running the latest drivers (and if there are firmware upgrades for it, install those, too). You shouldn't have to go without sleep. It's just not natural.

Hibernating, BTW, is different from sleep in that the computer is actually off. If I understand correctly, with Windows hibernation, the contents of RAM get paged out to the backing store, along with the current CPU registers. Upon powering on, the file containing those registers is detected, the CPU registers are restored, along with any pages that were previously marked non-pageable (e.g. the memory maps for all the processes, socket/pipe/whatever state). Then, execution of the kernel continues, probably at the return address of the top stack frame. As execution continues, memory gets paged back in from disk as needed, and everything just sort-of-magically works.

By contrast, with sleep, the CPU registers get shoved out to RAM and the contents of RAM doesn't get paged out. The CPU sends a message to the PMU (power management chip) that says to start sleeping, then halts itself (like it does when the machine shuts down). Then, the PMU shuts off power to the CPU while maintaining power to the memory controller portions of the northbridge so that memory is maintained. On wake, the CPU loads its instructions from a serial ROM/boot ROM/whatever. One of the first things it does is poll the PMU to see it is already active. If so, it doesn't continue booting, and instead, loads its registers from RAM, culminating (I think) with a jump to the return address on the top stack frame.

Of course, this is only my rough memory from having read discussions of the process on various Linux-powerpc lists. I don't deal with the PMU much (except in the distant past, mucking with the pseudo-ADB side of it on laptops), so I can't guarantee that it is even remotely accurate. Just a rough approximation of what happens.

There are two main differences: 1. waking from sleep is almost instant, while waking from hibernation takes a few seconds and the system is slower while everything gets paged back into memory, and 2. hibernation uses no battery power, while sleep requires some battery power.

 

[gururyan]

Rip Van Winkle

My 733/G4 has problems waking up sometimes. I have narrowed it down to usually only happening if Classic was running when it went to sleep, so I make sure and stop Classic before putting it to sleep at night. Why do I not just Shut Down?...because it won't, it just restarts. I can rarely get it to Shut Down the right way, I have to do it the "incorrect" way. I have to wiggle the mouse all over the toolbar to wake it up from a sleep. So frustrating at times.

 

[Elmo89m]

There was a report on this a year or two ago that said a computer running nonstop only tacks on a few dollars to your electricity bill.

a month or a year?

 

[noodles2k5]

It was like $20 a year.

 

[Afficianado]

If your computer is having problems turning on, but not having any problems staying on, chances are the problems are in a switch that is wearing out because you've been turning the computer on and off nearly every day for a few years. Replacing the power supply has a very good chance of fixing the problem, but keep in mind the problem might also be in the motherboard, or even the physical power switch on the front of the case. In any case, Microsoft Windows tends to get crudded up if left on over time, so reboots become necessary. As long as you can perform a soft reboot without cycling the power, I'd say it's safe to leave the power on, while rebooting every once in a while. Before you do, though, take a can of compressed air, open the case, and blow out all the dust. The risk of overheating is proportional to the amount of air circulation. If you notice fans starting to go out, power it down.