They can't.

This build is terrible except for the CPU + Mobo + RAM which is quite solid.

1. 740s should be replaced with a Radeon R9 280 or GTX 960.
2. CPU Cooler should be dropped and just go with the stock Intel cooler.
3. Monitor is really small, should be able to bump it up to a 23-24" 1080p monitor without that big of jump in price at all.
4. Would replace the 450W PSU with a 500-550W PSU that's at least 80+ Bronze.
5. UPS shouldn't be factored into the build price, good to have one though.