What is the fundamental difference between KVR13S9S8/4 and KVR1333D3S9/4G?

Question

Iron

The fact that one has 4 chips, and the other 8 is understandable.
I can not find how this can affect performance or work in tandem with another KVR1333D3S9 / 4G

Answer 1

If both start up, they will work in pairs without problems.
In principle, there is only one difference - the capacity of each memory chip - for KVR1333D3S9 / 4G - 2 Gb, and for KVR13S9S8 / 4 - 4 Gb. And for example, the H55 chipset and its relatives do not understand 4 Gbit chips, the memory can be detected correctly, but the operating system will not work.
From Faq Kingston
https://www.kingston.com/memory/desktop-notebook
Why doesn't the new DDR3 memory work with my computer even though it has the same specifications as the old memory?
This may be due to chip density, especially if your system is based on older DDR3. Your system may require 2Gb (gigabit) DRAM chips, and the memory you installed has a 4Gb chip density that is not compatible. Manufacturers of DRAM chips no longer make 2Gb chips (not to be confused with the term "gigabyte", which refers to memory capacity). Therefore, we cannot produce compatible modules.
FAQ: KTM-073115-DTN-01

Answer 2

Some older motherboards may not support dual-rank memory. And it's better not to mix them. Doesn't affect performance.

Answer 3

Timings. Moreover, you need to watch not only the most common CAS Latency, RAS to CAS delay and RAS Precharge time, but also the rest, if you want to understand it in detail.
Chips. Look at the marking of the chip, find the datasheet for it, see how they differ.
This is all, of course, if you understand.
At the household level, it is believed that memory works best in paired banks - that is, you should not mix dims built on different chips - it will work, but at the speeds of the slowest bar.