Just wanted to share my overclocking experience with coffeelake and z370 Taichi.
My first mobo on z370 was Asus Strix-F, where I think the F stands for failure I bought it right at the launch, same as with my first coffeelake CPU. Thought highly about ROG-brand, and it was pretty much the only board available from the store I got the 8700K so .. yeah.
What was wrong with the strix top-3:
on higher volts (1.35 and above) it kept shutting itself off when doing Prime-95 with AVX small-fft, turned out that the VRM could not handle more then 200w package power draw
RGB-leds were bugged, they were on always even though set to disabled from BIOS. Small issue, that persisted on multiple BIOS-updates and was/is VERY annoying!!
memory overclocking was bad, was not able to go past 3900Mhz with my memorykit (3600CL15 now runnin 4266MhzCL18 on Taichi)
..among other things
But anyways. So I heard a lot of good things about Asrock Taichi from overclocker friends. Said to be amazing board for the money, and indeed the feature list is way above it's price point. AC-wifi (though only 433megabits), two intel gigabit ethernet-ports, three m.2 slots, dual-bios etc. Only 220 euros, which was actually about 10 euros cheaper then the Strix, so I bought one. Also at the same time I wanted a new try on the silicon lottery of the CPU, so I bought a new one to go with Taichi.
The new CPU is not a big step-up from the previous one, OC's a little bit better with a little lower volts. Still needs 1.408 for prime95-AVX. Previous needed 1.43, so a little better.
But the Taichi... Taichi has really surprised me in a positive way! The VRM handles up to 290W w/o trouble, my CPU is 5Ghz prime-95 AVX "stable" with small-fft while package power draw is hovering around 280W on a two hour run I realize that it is not safe to run that much current through your VRM & CPU for so long, but I had to try it and it works! Needless to say that it is also stable with a lot lower power on 'lesser'-AVX benches and burners like LINX, IBT, x264 loop-bench, Real Bench.
LLC1 (tight LLC) is reporting very little deviation from set value in HWiNFO64, and higher LLC-levels let the CPU droop while under load. So LLC working fine.
Then memory OC. Holy Crap. Amazing. Ridiculous. Perfect. Asrock is really pushing the ceiling up for 4-dimm slot mobos. Asus has a tight competitor for their Apex, from a 150e cheaper board with four dimm-slots My only gripe is that with auto-settings the third timings training is not optimal, but this could be fixed with bios update i think. I was a little puzzled why my read-speeds were dropping from 55k (xmp) to 44k in Aida64, but figured it out by playing around with the third timings. My stable settings for 3600MhzCL15 G.skill samsung b-die kit is 4266Mhz CL18-19-39. I have done a lot of benches with 4266CL17-18-39 settings, and even though it flies through benchmarks for hours and hours, thousands of percents covered, with LINX and Prime Blend all OK I still get random crashes in games.
For memory overclocking on Taichi you need to be lucky on two things: CPU memory-controller and your dimm sticks. I think I am on the "luckier" end of the spectrum, I can boot to 4300Mhz CL19-19-39 but it is not stable. Albeit close to being.
But there are people who are "luckier" then me, and have reported Taichi reaching up to 4400Mhz on the memory with CL19 timings, like here:
Credits to Divvy on io-tech.fi forums. Amazing results, though he is still in the middle of testing them stable. Still, to even boot with those numbers on FOUR DIMM SLOT MOBO! Good job Asrock!
Now to the 'technical details'.
I have delidded my CPU. Currently I am very satisfied with the following settings: CPU multiplier for all cores 50x, no avx-offset (auto), CPU-powerlimits at max, V-core on 'offset', -30mV. Dram 1.5V, VCCIO 1.19 VCCSA 1.29 Memory 4233MhzCL18-19-39.
In games my vcore hovers around 1.31-1.34, where my temperatures are around 45 to 55'C. In benchmarks like x264 and realbench my temps go to around 70-75'C while vcore is around 1.37 to 1.39. Prime95 AVX Small-FFT (newest version of prime) raises the temps up to 85-88'C and vcore initially peaks to 1.424 at the start and then setles on hovering around 1.392 and 1.408, max temps after two hours (my longest run) just little shy from 90'C but none of the cores went above. On desktop I drop down to 0.5V with 800Mhz, idle temperatures around 28 to 30 'C where my CPU-fans are also idle. I am using alphacool eisbaer AIO, 240mm copper rad, with corsair ML Pro fans.
I have had this mobo now for more then a month, and I have run countless of hours of games (PUBG, Overwatch and some others) with it and the settings above with memory on 4266CL19 , and also done a little bit of video editing, office work and such. Not had any crashes since passing benchmarks.
Asrock Taichi has been very solid platform for me. It does what I need it to do, and the memory-wizardry that Asrock has pulled off is awesome!
Here are some videos; at first it is me butchering a perfectly innocent i7 8700K with a knife and installing it on Taichi:
Then it is me doing some overclocking:
And the grand finale is me doing a close-up on memory OC'ing, stability benches etc:
I wanted to post this as a 'heads up' for people who are looking for a cheaper alternative to 300++ euro motherboards. Taichi is selling for 220 euros or less, and is able to match super-highend boards like Asus Apex when it comes to overclocking.