[HARDWARE] Mac Questions -

Dan Oetting dan_oetting at uswest.net
Mon Mar 11 12:46:49 EST 2002

on 3/11/02 9:00 AM, George wrote:

>1. can I pause / stop the program to  change monitors (do I really need

You need to at least put the system to sleep if the monitor resolution 
changes. Hot swapping monitors is not recomended (although I do it myself 
on occasion). There is a slight possibility of damaging the monitor or 
computer. Always turn the monitor off first.

Many macs can run headless though a few will not boot without a monitor. 
Plugging in a VGA adaptor will fool the mac into thinking a monitor is 
attached and define a monitor resolution so you can access the machine 
remotly via Timbuktu.

>2. "      "        "         "        "         "   change the mob, add
>Ram, etc?

It's generally recomended.

>3. how often does the Cruncher dial-out? I have 170 days to go on an LC
>III+, 12 MB of Ram.

You can set that in the preferences or disable it and flush the blocks 
manualy. Is the 170 days the time before your LCIII gets replaced? Or 
does the client say it will take 170 days to process the blocks in the 
buffer? If you got a new G4 you could complete all those blocks in part 
of an afternoon.

Unless you are going on vacation your buffers should not be larger than a 
few days worth of work. There is half a chance that RC5 will be over in 
170 days and none of your blocks will be counted.

>4. does  a Ram disk speed things up?

A ram disk won't speed things up but if you can enable the energysaver 
you won't have to listen to the HD spinning all night.

>5. any advice welcome - what about power failures?

After a power failure the client will restart from the last state saved 
on the HD. If you have checkpointing enabled you will only loose up to 
one checkpoint interval of work. Otherwise the client saves it's state 
after every block so you only loose the current block. If you run a ram 
disk you loose the entire buffer.

Compute the cost of the electricity to keep this machine running when the 
only thing it's doing is crunching blocks. Divide the electric cost by 
the time it takes you to process 1 block to get your cost per block. Now 
divide the $10,000 RSA prize by number of blocks remaining in the contest 
to get the expected gain per block (currently that's $0.0000005 or 1/20 
thousanth of a penny per block). If your computer uses only 5 watts and 
it takes an hour to complete a block and electricity is $.10 per kwh your 
cost per block is $.10/1000 * 5 /1 or $0.0005. Your costs are 100 times 
larger than your expected gains so why do you do it?

If you are running the client to contribute to the global cause let's 
look at the global numbers. If we multiply your cost per block by the 
total number of blocks processed so far we get $0.0005 * 68.7 trillion = 
$34+ million. This is the cost of electricity alone that has already been 
burned by the distributed.net clients cracking RC5-64. And we can expect 
to burn another 5 million before the key is found. Is it really worth it?

-- Dan O.
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