Two PSUs in same computer?

[sunnyUK]

I'm investigating options for a new machine that will be used mainly for storage. I'm likely to need a lot of disks, and instead of upgrading my current (nice and quiet) PSU, I've been thinking about putting an extra PSU in to power the drives.

Both PSUs will be connected to the same wall outlet, so they'll share a common earth.

Is there a risk involved in doing this? Does it make any difference if +5V on the rails to the disks are actually +4.99V whereas +5V to somewhere else is +5.01V ? The only connection between the two subsets will be the datacables from disk controllers to disks.

And a second question, if I may: Does the power up sequence matter? Obviously there needs to be power to the disks before the BIOS attempts to boot, but is it a problem to switch on the PSU that drives the disks before switching on the one that drives the mobo?

Thanks in advance for any help,
Tomas

[ultraboy]

Is there a risk involved in doing this? Does it make any difference if +5V on the rails to the disks are actually +4.99V whereas +5V to somewhere else is +5.01V ? The only connection between the two subsets will be the datacables from disk controllers to disks.

I do not have enough technical knowledge to answer this intelligently, but from personal experience using dual psu set up for more than 6 months I have not seen any problem yet. *knockwood* I was told to ensure that the MB and VGA are powered from same PSU to avoid "cross talk" (whatever that mean ) as VGA also receive power through MB.

..Does the power up sequence matter? Obviously there needs to be power to the disks before the BIOS attempts to boot, but is it a problem to switch on the PSU that drives the disks before switching on the one that drives the mobo?

What I did was having the 2 PSUs start at the same time. I use relay method as described in this article at Speedy3D.

Hope this help.

[sunnyUK]

Thanks ultraboy, that is a good help. Nice and easy way to get the 2nd PSU powered up simultaneously.

Glad to hear you haven't had any problems with the dual PSUs. I hadn't thought about ensuring that the mobo and VGA was powered from the same PSU, but by pure chance the layout I have in mind only used the 2nd PSU for the disks, so this would have been achieved anyway (but luck, rather than by design). Now I know what to look out for.

Thanks for the help.

Kind regards,
Tomas