How to tell which DDR4 memory for Ryzen you are buying
Here's how much you can tell by looking at the box when buying memory:
Before you buy -
1) serial number barcodes on the box tells chip maker but not die type:
• G-skill symbols 1-4 are year & week, symbol 6 is chip maker. 4 Hynix (Hyundai), 5 Samsung; e.g. 1701A400xxxxxxx is Hynix.
• Kingston (HyperX) symbol 4 is chip maker: H Hynix, M Micron, N Nanya, S Samsung, E Elpida, K random, symbols 5-6 are # of chips: 08 single-sided, 16 dual-sided, symbol 7month,8-9 year.
• Corsair symbols 1-4 are year & week, chip maker only visible on chips label: ver2 Elpida,ver3 Micron, ver4 Samsung, ver5 Hynix. Some boxes have a window.
• Crucial uses Micron chips.
2) see if the model of planned purchase is listed in http://www.overclock.net/t/1627555/ryzen-memory-ic-collection-thread#post_25997823
3) find chip maker with Thaiphoon Burner (softnology.biz) - search database in Tools-SPD Browser, select class DDR4, download.
4) find rank or sides in larger QVL lists as in http://download.gigabyte.cn/FileList/Memory/mb_memory_ga-z270x-gaming8.pdf
or in https://dlsvr04.asus.com/pub/ASUS/mb/LGA1151/STRIX_Z270G_GAMING/STRIX_Z270G_GAMIN_Memory_QVL.pdf
After you buy -
5) verify/submit your chip info to Thaiphoon database: in EEPROM-read SPD; it may ask if your chip is not in their database.
actual speeds from experience:
Corsair Vengeance CMK16GX4M2B3000C15 15-17-17-35 is Hynix dual-sided 2x8GB ran 2666-16-16-16-36
G-Skill Ripjaw V F4-3200C14D-32GVR 14-14-14-34 is Samsung dual-sided 2x16GB ran at 2666-16-16-16-36
G-Skill TridentZ F4-3400C16D-32GTZ 16-16-16-36 is Samsung B-die dual-side. 2x16GB ran fine to 3200-18
G-Skill TridentZ F4-3400C16D-32GTZ another pair with Samsung dual-side 2x16GB ran at 2666-16-16-16-36
G-Skill TridentZ F4-3200C16D-16GTZB 16-18-18-38 is Hynix M-die single-side 2x8GB ran 3200-14-16-16-36; same chips as 4x8GB (32GB) runs 3200 with relaxed timings 18-18-18-38.
Dual channel - two DIMMs are a matched pair. Quad channel (as in C16Q-32) is four dimms. Slight speed difference.
Dual sided - chips are mounted on both sides of DIMM. This may be peeked visually. Single is preferred (less data traffic per memory socket).
Dual rank - data channel width. Slight speed difference. CPU-Z can tell if your memory is single or dual rank.
Faster memory (3000, 3200, 3400 and above) may reach 2933 or 3200+ speed with faster Ryzens.
Samsung B-die usually is in 3200-14 or 3400-16 or faster rated (costlier) kits.
Fastest Samsung may reach 3200 and above.
Hynix may reach 3200.