I know it needs to be pure sine wave, but what I dont know is if it needs to output 1000watts. I won't even be close to using a full 1000 watts in my build, but as video cards keep dropping in price I may be in the future with quad sli.
The solution I am looking for is now, so any input the wise folks here can provide would be greatly appreciated.
You size your UPS to the actual draw of the computer (plus anything else you run off the battery).
And it's OK if you don't size for a gaming workload either. Sure, the computer will shut down if you have a power outage while gaming. If you're major concern is work in progress that needs saving during a power outage you can size for that amount of power.
Unless it's a 'mission critical' computer that needs to run for an extended time on battery power a pure sine wave UPS isn't actually required. Stepped sine wave is good for a home or office PC.