I'm putting together a budget PC with an i7-8700, 16GB of Corsair Vengeance DDR4-3200 memory in a 2x8GB kit, and a 512GB SSD. I'm concerned that 16GB may not be enough and am considering adding another 8GB DDR4 stick from the same brand and speed. Would running three populated memory slots cause performance or compatibility problems?
4 Answers
With three sticks, the motherboard can generally use dual-channel mode for the portion of memory that has matching capacity, while the extra 8GB operates in single-channel mode. That means you’ll have more total memory, but performance may drop once workloads spill into that unmatched section.
Adding a third module isn’t guaranteed to cause problems, but it puts more load on the CPU’s memory controller and can make the advertised speed unreliable. You may need to enable a lower speed such as 2666 or 2400 MT/s, adjust settings manually, or reset to default settings if the system fails to boot.
If possible, I’d look for a matched 2x16GB kit instead. A used kit can also be reasonable, as long as you test it and are willing to run all the modules at the speed and timings of the slowest stick.
It should work physically, but three sticks usually won’t run as cleanly as a matched two- or four-stick setup. The system may lower the memory speed or require more relaxed timings, so don’t assume the full 3200 MT/s will be stable.
I know two sticks would be better, but RAM prices are tight. If the third stick is affordable, having more capacity can still be preferable for applications that are actually running out of memory.