Is DRAM:FSB Ratio still a thing with Ryzen, what should it be?

is DRAM:FSB Ratio still a thing with Ryzen, what should it be?

Not really but kinda?

The equivalent is infinity fabric clock and it should be 1/2 you ram clocks in almost every case except for extreme overclocking.

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Aida64 reports a 45:3 ratio on my friends Ryzen machine, my guess it’s it’s reading reading a stat and trying to report it back but, doesn’t know how?

The context of the question is me and friend until last year have been running over clocked core 2 quads and we all upgraded to Ryzen. We got some what familiar with the C2 chipsets and platforms but, with Ryzen you don’t go and up the FSB x amount of MHZ for y overclock. Having a 1:1 DRAM to FSB seemed to to help in those days, at least for us.

I’m not sure what its measuring. FSB doesnt exist in the same way that it did for the C2D. Infinity fabric is how you interface the cache with the ram but also how the cores interface with eachother. the clock is actually the same as the ram but because ram is DDR its shown as double the speed of infinity fabric. If you run anything other than half the speed reported for your ram you run into penalties for timing.

For Zen and Zen+ I dont think its possible to set infinity fabric to anything other than half of your DDR which is why faster memory means faster CPUs even though core clocks arent increasing.

On Zen2 you can set IF clocks manually but its not really worth it unless you’re going for big overclocks on memory.

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Socket 775 and earlier Intel CPU’s had the memory controller on the chipset, so the FSB directly affected everything. The northbridge memory controller had to refresh the RAM which is why all Socket 775 boards had to run a 2T Command Rate for the RAM. Even back then the Athlon 64 CPU’s used an integrated memory controller using the Hyper Transport Bus:

The third paragraph there give a little insight. Since the memory controller moved to the CPU and newer buses have come about, there is no longer a need to lock down the RAM to a multiplie of the FSB. Plus with UEFI and XMP profiles you mostly can select a supported ‘speed’ and it just works. There is a DRAM Calculator for Ryzen, but I haven’t used it. Being lazy, on Linux, and my RAM running 3200MHZ out of the box has been sufficient for me.

If you really want to squeeze out every last bit from your RAM, look up guides for DDR4 and Ryzen memory overclocking. Things have changed a lot.

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