Old HP ML570 G1 Server - Triple CPU?

[badass]

Firstly I know that all CPU's in a server should be from the same bach, however is it just for stability, is it paranoia that doesn't matter in the real world, or is there ANY risk of irreversible damage to the hardware - CPU's or anything else?
I cant see there any reason to be, but I'd rather not fry the server.
As far as I can see, the Power regulators for the CPU's are in the CPU daughterboards so I needn't worry about frying the server because I have plugged a CPU in with no power regulator.
The thing is, I have 2 ML570 G1's with the same PIII Xeon 700/100/1MB (IIRC) CPU's. One has 2 CPU's, one has 1. This server is running several virtual machines, but really needs another 1-2 CPU's.
Has anyone in the past just plugged in an extra CPU of the same speed/specs in an old HP server - any type? What happened?
I am grateful for any usefull advice

[Moby-Dick]

I've never run with 3 CPU's before... I'm sure SMP wont like it very much ( or possibly wont use it )

[arthurleung]

Checked some Dell servers' configuration and I've not seen any 3CPU configuration available. I doubt its gonna work. It won't kill CPU, just probably won't boot.

CPU doesn't need to come from the same batch. (Well, except overclocking when some batches overclock better than others)

[d3fiant]

Ive worked with ProLiant's for a loooong time, never seen any 3-way setups. Ive moved around plenty of CPU's but always 1-2, 2-4 or 4-8. The scary part is I just assumed that was how SMP worked and have never tried it otherwise :S bad me

[sjbuck]

Fairly certain 3 CPU won't work, stick in 4 and see what happens.