Considering RAM upgrades but not sure on the speed.
Considering RAM upgrades but not sure on the speed.
You're considering a RAM upgrade from 8GB to 16 or 32GB. Your current setup uses 2x4GB at 2666MHz DDR4. The motherboard supports up to 4000MHz, but your CPU only handles 2666MHz. For the new RAM, aim for speeds that match your CPU's capabilities—typically 3200MHz is a safe choice. Check the latest specifications in your motherboard manual for exact guidelines.
The traces on the motherboard and the memory controller have their rated speeds. While they list 2666MHz, they can handle more than that. Using an XMP profile will push your memory over its limit, and most controllers should still function properly. However, it's worth noting that Intel chips from that era don't gain much from higher memory speeds unless you intend to upgrade later with a newer CPU.
DDR4-3200 works well with 9th generation Intel processors. If you’re purchasing a new kit without pairing it with existing RAM, consider DDR4-3200 or DDR4-3600 for better value. By this stage, CPU memory controllers have improved, allowing most chips to support these speeds, with some even reaching DDR4-4000. In contrast, older AMD CPUs often couldn’t reach higher frequencies. Overall, RAM compatibility depends more on the CPU’s controller than raw speed claims. Community testing and reviews guide optimal settings, while official specs usually underperform in real-world use. If you’re not following PC hardware trends, sharing your setup helps others too.
Just purchase whatever cheapest 3200c16 or 3600c18 32gb package, disregard the manufacturer names since they don’t matter much (those memory chips are produced by similar companies). Keep in mind it’s a single unit and this CPU socket is pretty unreliable. Clearly, a 4000+ MHz build is possible with enough voltage, but you should aim for around 1.45V for stable operation over time. If you plan to modify the RAM, consider used M378A1G43EB1 sticks, four 8GB quad modules from Samsung, and ensure your scaling is above 2V to avoid issues. A voltmodified motherboard that supports more than 2V would be ideal. You can get decent timing, especially with TRFC or a M378A2K43DB2 in the 2666-3200 range, paired with two 16GB dual-channel Samsung dies. Overall, it’s likely safe as long as you manage the voltage and use quality components.
The vendor catalog from Asus details every memory model they've verified works with the TUF Z370-Plus Gaming board. I've included the referenced PDF for your reference. If you wish to keep your current RAM, the new module must match the existing clock speeds, which caps performance at 2666MHz. It seems your HyperX Fury 8GB (2x4GB) at 2666MHz is eligible if it supports CL15 timing. You might find a comparable model at a better price, especially since DDR4 up to 4000MHz is available on the board with XMP support. Keep an eye on the QVL for memory compatibility details and possible configurations. TUF-Z370-PLUS-GAMING-Memory-QVL.pdf
I just found another article that said DDR4 3600MHz runs fine with the i5 9600K. They recommended Corsair LPX 3600MHz C18. So it looks like 3600GHz seems to be the sweet spot on terms of price : performance. Here's a helpful article that explains what all those numbers and letter mean in different manufacturers' model numbers. It can be helpful when comparing what is for sale at your favorite vendor doesn't exactly match the number on the QVL. Sometimes the only difference is the code for the color of the heat spreader. https://raisonjohn.blogspot.com/2019/01/...rs-of.html
Thanks to everyone, I've gained better insight into RAM and will make more informed purchasing choices. I plan to purchase a dual 8GB or 16GB DIMM kit at 3200MHz, following the Qualified Vendors list from @Michael C.
For DDR4 users, Samsung B-Die stands out as the top choice, offering strong overclocking potential beyond your CPU's limits. Teamgroup lists it around $47 on Newegg; doubling that for a 32GB package gives solid performance.