What UPS do i need for my HP G5 tower server. ?

There is no UPS on the market that can go 6-10 hours. Most are rated for somewhere around 5-10 minutes, possibly as high as 40 minutes if it’s a top of the line unit with a large battery, and your computer power draw is small.

You can get a backup of 6-10 hours, but only with a generator. That’s the only thing I know of that can generate power for that long in the event of a power outtage. Even the highest-end server UPS’s only run for 2-3 hours.

Now, if you meant to say 6-10 *minutes*, you can generally squeeze that out of a UPS with 500VA or higher.

Two of the most commonly used UPS manufacturers are Tripplite: http://www.tripplite.com/ and APC: http://www.apc.com/

You can read more information about UPS units here: http://en.wikipedia.org/wiki/Uninterruptible_power_supply