Switch it to whatever voltage your country uses. Doesn't have to be exact. 110 in 115 outlet is ok.
Biostar T-Force series is made for overclocking. The bios may have memtest built-in. By default, bios boots disks up. It can be set to boot to memtest. If you need a pointer, post in o/c section.
What's the make & model of the psu?