[Sosa]

Greetings,

I would like to hear expert opinions on whether the constant running of SETI degrades your CPU and or decreases lifetime of HD. I've heard conflicting opinions in this thread.

I was told by an Apple tech that heat decreases CPU performance and lifetime. This is why computers should be run in cool environments. This makes sense to me. When running SETI I take precautions to ensure my comptuer (an iBook) receives adequate cooling during the night.

But what about the HD? I was under the impression that SETI ran its computations using RAM or the 512 kb cache, and that it did not need to access the HD except when completing a unit. But I have other people telling me the HD is always spinning when the computer is on, and others saying SETI does access the HD. I'm concerned because although I do want to contribute to SETI and I'm willing to pay a small cost, I am not interested in significantly reducing thelifespan of my iBook!

Thanks for your comments.

[reader50]

SETI writes out intermediate results at regular intervals, so if the client is suddenly quit, it will pick up near where it left off.

When this feature was designed several years ago, it wrote data out every 30-120 minutes depending on how fast your box is. Today, systems are so fast that some write data out every minute.

If you move SETI to a RAM disk, you eliminate all HD access. The HD can be spun down, and will remain spun down. This was easy under OS9, but is a bit more involved under OSX.

Naturally, running from a RAM disk carries the risk of total loss of the current work unit if the system crashes or loses power. Since a modern system finishes a work unit in a few hours, this is not the risk it used to be when a work unit could take over a week to finish. At the time, a system crash 5 days into the unit would mean losing a lot of work.

[OneMacGuy]

Originally posted by reader50:
SETI writes out intermediate results at regular intervals, so if the client is suddenly quit, it will pick up near where it left off.

When this feature was designed several years ago, it wrote data out every 30-120 minutes depending on how fast your box is. Today, systems are so fast that some write data out every minute.

If you move SETI to a RAM disk, you eliminate all HD access. The HD can be spun down, and will remain spun down. This was easy under OS9, but is a bit more involved under OSX.

Naturally, running from a RAM disk carries the risk of total loss of the current work unit if the system crashes or loses power. Since a modern system finishes a work unit in a few hours, this is not the risk it used to be when a work unit could take over a week to finish. At the time, a system crash 5 days into the unit would mean losing a lot of work.

My wifes old Supermac Macintosh clone has been running the SETI screen saver for many years with no problems that I can detect. It has the original 4 GB SCSI drive and a G3 processor that I put in it probably 5 years ago. I think that the thing to watch out for on processor temps is that your CPU is adequately cooled and does not get TOO hot, even when under the 100% CPU utilization SETI puts on it. Her G3 processor runs at about 105 degreees F under load. Not hot enough to degrade CPU life and well within Motorola's specs. Reader50's comments on using a Ram Disk is good though, especially on a laptop. The drive is slow anyway, it would almost certainly run faster and allow the drive to spin down when not in use.

[mikkyo]

I've run distributed computing apps on my 700Mhz iBook for 2 years continuously, and on my first iBook for 4 years continuously.
Both machines are set to never sleep the hard disk or CPU, but the display is set to sleep.
I have the rear of both propped up at an angle to allow better venting.
I haven't had any problems.
However, both iBooks are technically outdated and the drives should fail sometime in 4-5 years of continuous use, and I don't really care.
You may care, you may not want to risk shortening the life of your machines, of course your machine could die in a week from some completely non-related issue too.
Either way in 2 years, it probably won't have died, and the newer technology will make it way outdated. You'll get a new one then or at least want one real bad.

Just don't leave your iBook on a bed or carpeted floor for very long, the softness of the materials envelops the vents and helps it retain heat.
Very bad.

Who knows, maybe in a year you will run out of space and put in a bigger hard drive, further extending the life of the machine.

The CPU should last, I have a 50Mhz 68030 that is still running fine and it gets hot enough to burn you if you touch the heat sink.

[OneMacGuy]

Originally posted by mikkyo:

The CPU should last, I have a 50Mhz 68030 that is still running fine and it gets hot enough to burn you if you touch the heat sink.

And which DC Client are you running on this box? Could only be SETI? Unless you are running some old ?nix flavor. Or is it relegated to "antique" status?

[mikkyo]

The 68030 runs unix(netbsd I think, I haven't had to touch the machine for years), and acts as a router and backup host for an internal network, it doesn't DC any more.
I did run SETI on it ages ago though.
My point was that the CPU shouldn't burn up as long as it is properly cooled.

Ya know now that I think about, I can only think of one dead mac processor I have ever had. It was a 68020. Heh.
I've killed a couple of athlons though.
I know other people that have burned up their powerbooks, ibooks though.
Scott killed his TiBook how many times?

[Scotttheking]

Originally posted by mikkyo:
Scott killed his TiBook how many times?

This is the first thread I'm reading on my newly repaired Tibook!
This was somewhere between #6 and #8.
If you want to hear the story, just ask

[gumby5647]

Originally posted by mikkyo:

The CPU should last, I have a 50Mhz 68030 that is still running fine and it gets hot enough to burn you if you touch the heat sink.

Ever touched a 601 after awhile? Wowsers!