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RAM, what you need to know.

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Xaltar View Drop Down
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Joined: 16 May 2015
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    Posted: 28 Apr 2020 at 11:09pm
I see people complaining about RAM not running at it's advertised speeds all the
time on the forums. This is a misnomer that I repeatedly have to explain so here
I am explaining everything in one place for anyone that needs the info.


RAM uses 2 factors to determine frequency:


JDEC (sometimes called SPD) - This is the RAM's default frequency(/s). It is a
                                              collection of timings and frequencies the RAM is
                                              actually designed to operate at. This is guaranteed

XMP (eXtreme Memory Profile)- This is a saved overclocking profile that the RAM
                                              manufacturer has fine tuned and tested on a broad
                                              spectrum of systems. It will almost certainly work
                                              on system configurations it was tested with but is
                                              not guaranteed to work on all systems.


Here is a screencap of SPD settings taken from CPU-Z (a free app)

These profiles are saved on the RAM sticks themselves on a small chip called the
SPD chip. XMP is most often only tuned for one system type (AMD or intel). This
is why you see "Ryzen Ready" or "intel Ready" on some RAM packaging. The memory
controller on intel and AMD CPUs operate differently. This is why what works on
intel doesn't always work on AMD systems and vice versa. This has improved with
new CPU generations as both sides try to improve compatibility but is still
problematic even now.

So, when you are buying RAM, please look at the RAM's product page to at the very
least check if it is tuned for intel or AMD before buying and ensure that it is
tuned for the system you plan to build. If your RAM does not run at it's XMP
rating it does not mean you have a defective motherboard, far more likely is that
you are using RAM that has an XMP profile that is not tuned for your system (AMD/intel).

There are ways to manually set your RAM's frequency and timings, essentially
tuning your overclock for your system. There are a lot of guides about this
available on the internet so have a look for one if you are not able to get your
RAM to run at it's XMP speed. Sometimes however, the RAM is just not compatible
so this is not a guarantee.

Edited by Xaltar - 28 Apr 2020 at 11:19pm
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