sharing a power supply

Dean Johnson dtj at
Wed Jul 2 14:24:33 EDT 2003

On Wed, 2003-07-02 at 12:41, Alan Ward wrote:
> Dear listpeople,
> I am building a small beowulf with the following configuration:
> - 4 motherboards w/ onboard Ethernet
> - 1 hard disk
> - 1 (small) switch
> - 1 ATX power supply shared by all boards
> The intended boot sequence is the classical (1) master boots off
> hard disk; (2) after a suitable delay, slaves boot off master
> with dhcp and root nfs.
> I would appreciate comments on the following:
> a) A 450 W power supply should have ample power for all -
> but can it deliver on the crucial +5V and +3.3V lines? Has anybody
> got real-world intensity measurements on these lines for Athlons
> I can compare to the supply's specs?
> b) I hung two motherboards off a single ATX supply. When I hit
> the switch on either board, the supply goes on and both motherboards
> come to life. Does anybody know a way of keeping the slaves still
> until the master has gone through boot? e.g. Use the reset switch?
> Can one of the power lines control the PLL on the motherboard?

Use two power supplies, one for the master, one for the slaves. Not an
optimal solution.

How long will PXE sit around waiting? Is it settable? If it will wait
long enough, it won't matter how long it takes for the master to boot.



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