What about motherboard/chipset bus characteristics?

[shavais]

Is it no longer true that motherboard/chipset bus speeds substantially impact performance? How many memory transfers can these motherboard/chipsets perform per second? (Obviously that depends on the CPU, but isn't there a motherboard/chipset imposed limit?) And things like the ability of the CPU to perform writes and reads simultaneously over a given bus? Why am I finding it so hard to find that kind of information on modern motherboards?

 

[TJ Hooker]

No, by and large that isn't true anymore. All CPUs for a given socket pretty much have the same bandwidth to the PCH. Only thing chipset really determines is how many PCIe lanes/SATA ports/etc you get from the PCH (although total bandwidth to the CPU doesn't change).

 

[Eximo]

For the simple reason that many of the functions that motherboard chipsets performed in the past have been integrated into the CPU itself.

CPU now contains its own internal power supplies, memory controller, I/O (PCIe), graphics (excepting some AMD CPUs and Intel's HEDT/Server chips). Now the motherboard will still have VRMs, but they are controlled by the BIOS essentially.

Intel's PCH basically has the disk controllers, USB, and a PCIe controller of its own. The CPU communicates to the PCH over a fixed amount of bandwidth, as mentioned above, so while you can have lots of devices hooked you will run into bottlenecks if they all need to communicate to the CPU at the same time.

I know less about AMDs chipset, because at the end of the day, it doesn't really matter all that much. You get a CPU, drop it in a compatible board, and you've shopped for a board with features you want. Everything else is just plugging the parts in.

Every CPU and Chipset has a block diagram you can review:
https://hothardware.com/reviews/intel-core-i7-8700k-and-core-i5-8400-coffee-lake-processor-review?page=2

You may to look up the various terms on their own to get actual bandwidth or frequency figures if you are interested.