Fastest DDR4 memory compatible with Intel Core i7-8700K?

For your situation, I would suggest being a bit cautious about chasing those ultra-high frequencies. I've been running an Intel Core i7-8700K on a Z370 board for years, and while the IMC (integrated memory controller) on 8th gen is pretty solid, it's definitely not a guarantee that you'll hit 4000MHz+ without some serious headache and potentially unsafe voltage tweaks to the VCCIO and VCCSA.

In my experience, 3600MHz is basically the absolute sweet spot for stability and performance on this platform. Honestly, the jump from 2400MHz to a nice G.Skill Trident Z Neo 16GB (2x8GB) DDR4-3600 CL16-16-16-36 kit will be literally night and day for your minimum frame rates in games.

Here's what I recommend based on my testing:
1. Stick to 3600MHz CL16: It's the most reliable "set and forget" speed for an 8700K.
2. Look for Samsung B-die: If you get a kit like the TeamGroup T-Force Dark Pro 16GB (2x8GB) DDR4-3600 CL16, you can tighten the sub-timings which actually helps more than raw frequency.
3. Watch your voltages: Going over 1.25v on IO/SA for daily use makes me nervous... keep it conservative to avoid degrading the chip.

Going for 4000MHz or higher usually hits diminishing returns highkey fast on Coffee Lake, and you might end up with random BSODs that are a total pain to troubleshoot. Basically, 3600MHz is the safe bet that still feels fast af. gl!

Interested in this too

Quick question - before I dive into the tech specs, are you planning on manual tuning or just clicking XMP and walking away??

I mean, 3600MHz is basically the *sweet spot* for value, but going higher gets pricey fast. IIRC, the 8th Gen controller can be kinda finicky past 3800MHz without some serious voltage bumps. If you're on a budget, 4000MHz might literally be overkill for the performance gain you'd actually see.

Exactly what I was thinking

So basically the consensus here is spot on. 3600MHz really is the limit for what I would call easy gains on an 8700K. Since you have a Maximus X Hero, you definitely have the motherboard headroom to push things, but the memory controller on the CPU is usually the part that gives up first. I've found that pushing past 3800MHz starts requiring way too much voltage on the VCCIO and VCCSA for my comfort level on a daily driver. If you're looking for a solid DIY project, I'd grab a kit of Crucial Ballistix 3600 MHz CL16 16GB DDR4 or even the Corsair Vengeance LPX 32GB DDR4 3600MHz CL18 if you need more capacity. The Crucial kits are especially fun because they use Micron E-die which stays cool and overclocks like a dream if you ever decide to manually tighten the timings later. Tbh, jumping from 2400MHz to 3600MHz is gonna feel like a massive upgrade anyway, you'll definitely see those 1% lows improve in games without needing to stress over 4000MHz stability.

Interested in this too

Building on the earlier suggestion, the IMC on the 8700K is usually the bottleneck before the motherboard is. Ive been running this platform for years and 3600-3800MHz is basically the wall for daily stability. Going higher usually requires pushing VCCIO and VCCSA to levels that arent great for long-term health.

• Look into Patriot Viper Steel 16GB DDR4 4400MHz CL19 and downclock it to 3600MHz with tighter timings. Its usually Samsung B-die and handles low latency well if you want to geek out on subtimings.
• Keep VCCSA/VCCIO under 1.25v. If it wont boot 3800MHz at those levels, just stick to 3600MHz.
• Mushkin Redline Black 32GB DDR4 3600MHz CL16 is a decent option that works well on the Maximus X Hero without much tweaking... basically a set and forget kit.

> 3600-3800MHz is basically the wall for daily stability. To add to the point above: it is honestly a bit of a letdown how finicky these 8700K chips get. I had issues with a build last year trying to hit 4000MHz and it just wasnt as good as expected... lots of blue screens and wasted time, unfortunately. The consensus here is definitely right about 3600MHz being the sweet spot for these. If you want real performance without the headache, maybe look at G.Skill Ripjaws V 32GB DDR4 3600MHz CL16 or the TeamGroup T-Create Expert 32GB DDR4 3600MHz CL18. They're both way more practical than chasing those expensive high-speed kits that might not even work. I'm happy to walk you through some BIOS settings if you have trouble getting the XMP to stick tho. Just let us know!