System memory is often the forgotten cousin among components when you're building a new PC. A lot of PC builders just buy whatever's out there, as long as it works in their systems. Some enthusiasts take the opposite route. They get expensive ultra-high-frequency or low-latency memory, hoping it will give them a big performance boost. You can pay from 30 to 100 percent more for these low-latency offerings, but are they worth the extra money? ExtremeTech examines the effects of low-latency memory on two high-end systems to determine its value to PC builders.