[SOLVED] How to find max usable RAM speed for 4 slots?

[HerbertSherbet]

I'm planning on buying 2x16GB of RAM (32GB total) for a new machine that I'm building. It's being built primarily to be a video editing machine but it will also be my general purpose computer. What I'm wondering is if I upgrade my machine in the future with a second set of 2x16GB RAM (64GB total) will I hit a cap or bottleneck with the MHz or timings?

I am still in the process of deciding on what RAM I should use. If I ever upgrade I will try to get identical specs so that I have good odds of it being compatible. So how do I find the limit that my CPU/Motherboard can handle? I have read through Intel's and Gigabyte's official pages but either haven't found it or haven't understood it.

Here are my specs:
CPU: Intel Core i7-9700K Coffee Lake 8-Core 3.6 GHz (4.9 GHz Turbo) LGA 1151 (300 Series) 95W BX80684I79700K Desktop Processor Intel UHD Graphics 630
https://www.newegg.com/core-i7-9th-gen-intel-core-i7-9700k/p/N82E16819117958
https://www.intel.com/content/www/us/en/products/processors/core/i7-processors/i7-9700k.html
https://ark.intel.com/content/www/u...9700k-processor-12m-cache-up-to-4-90-ghz.html

CPU Cooler: Noctua NH-D15S 140mm SSO2 D-Type Premium CPU Cooler, NF-A15 PWM Fans
https://www.newegg.com/p/N82E16835608072

Motherboard: GIGABYTE Z390 AORUS PRO LGA 1151 (300 Series) Intel Z390 HDMI SATA 6Gb/s USB 3.1 ATX Intel Motherboard
https://www.newegg.com/p/N82E16813145098
https://www.gigabyte.com/Motherboard/Z390-AORUS-PRO-rev-10/support#support-manual

GPU: SAPPHIRE PULSE Radeon RX 5700 DirectX 12 100417P8GL 8GB 256-Bit GDDR6 PCI Express 4.0 x16 ATX Video Card
https://www.newegg.com/sapphire-radeon-rx-5700-100417p8gl/p/N82E16814202350

PSU: Will be at minimum 30% higher than 97 watts above the final wattage rating of my parts with at least an 80% rating from a brand I can trust.

Memory: 2x16GB to be ran as Dual Channel. I can't imagine needing more RAM than 32GB but I want to stay flexible enough to upgrade.

Storage: 1TB of SSD storage as a boot drive with separate HDD storage added after the system is built.

 

[Rogue Leader]

Your RAM speed is limited by the ram you already buy.

Generally RAM you always want to buy in pairs (or 4's in the case of quad channel). Now can you buy more RAM and add it to the system? Yes, but there is a CHANCE it will not play right.

Your best chance of it all working together well is to purchase the identical ram kit you have already. Buying a different brand/model even to the same specs, can possibly not work.

There is no "cap or bottleneck" however once you get into the very high frequency ranges (like 4000mhz) some boards have issues running 4 dimms vs 2. That said I don't think you're looking to go that fast, and TBH that speed isn't worth the extra money. Your money would be better spent on a 9900k instead of the 9700k.

 

[HerbertSherbet]

Thank you for helping to clear that up. That puts me at ease. You mention caps in the 4000 MHz range. I'm not going to hit that with DDR4-3600 RAM, right? I know that you just said otherwise but it's a little close and I'm really wanting to build a machine that will have a long life if maintained well.

 

[Rogue Leader]

Thank you for helping to clear that up. That puts me at ease. You mention caps in the 4000 MHz range. I'm not going to hit that with DDR4-3600 RAM, right? I know that you just said otherwise but it's a little close and I'm really wanting to build a machine that will have a long life if maintained well.

Its not a cap, it just doesn't work, sometimes.

DDR4-3600 ram will never run any faster than 3600mhz which is far away from 4000mhz. If you run it at what it is rated at it should in theory last forever.