What does RAM Speed(OC) actually mean for Motherboard specification?

[Guest]

I know there are similar threads on this topic but still somehow I am looking for an understanding from layman's perspective.

Motherboard specifications for memory support mention like this

DDR4 3200(O.C.)/2933(O.C.)/2400/2133 MHz memory modules

What does say 2933(OC) really mean.
Does it mean that board might support 2933 Speed RAM or does it mean that board won't support 2399 speed RAM for sure but you may overclock a supported speed like 2400 RAM to 2933 and it should work?

There's also some explanation about XMP profile on other answers, any clarity on this would be great to know.

Thanks.

 

[wesleyh2003]

The OC frequencies are the maximum memory frequencies you can run by overclocking

 

[clutchc]

XMP is Intel's eXtended Memory Profile for automatically overclocking the RAM in BIOS. The (O.C.) speeds are what the board will allow you to set it at above the speed specified by the CPU's integrated memory controller.

 

[InvalidError]

More specifically, the highest speed the memory manufacturer has tested the memory at on their own testbench(es). The memory may still be able to reach higher frequencies with different motherboards and CPUs and may not necessarily be able to achieve those speeds on your own motherboard and CPU unless your combination has been specifically qualified by the manufacturer as such.

 

[Calvin7]

2933MHz is a memory clock frequency for Overclocking.(OC)

Ryzen - DDR Maximum Frequency Support Table(For better DDR4 compatibility, it is recommended to follow the table below to install DDR4 modules. Please refer to memory support list for more details.)
Maximum DIMMA1 DIMMB1
DDR4-2667 SR -
DDR4-2667 DR -
DDR4-2667 SR SR
DDR4-2400 DR DR
SR:Single-rank DIMM, 1R x4 or 1R x8
DR Dual rank DIMMs, 2R x4 or 2R x8

XMP sets memory parameters by enabling a profile in a single BIOS option setting.
Otherwise you would manually set:
1) DRAM frequency
2) DRAM timings
3) DRAM voltage

 

[Guest]

The OC frequencies are the maximum memory frequencies you can run by overclocking

So does it mean that in this example DDR4 3200(O.C.)/2933(O.C.)/2400/2133 MHz, native 3200 Mhz RAM won't work but I can safely install 2400 Mhz and OC it up to 3200?

 

[clutchc]

[/quotemsg]

So does it mean that in this example DDR4 3200(O.C.)/2933(O.C.)/2400/2133 MHz, native 3200 Mhz RAM won't work but I can safely install 2400 Mhz and OC it up to 3200?

[/quotemsg]

You can use any speed RAM in the machine you want. Your 3200MHz RAM will run just fine. It may or may not be able to reach its rated clock speed of 3200MHz and remain stable, but it can always be backed off to one of the lower speeds offered if not. You have to make that adjustment in BIOS. If you don't want to enter BIOS and make adjustments, the RAM may default to 2133MHz.

 

[Guest]

Thanks for the explanation. yes I get it now. I remember I installed a 400Mhz DDR1 RAM in my old Biostar AMD Socket A board that supported max 333Mhz and the inserted RAM was automatically down clocked to 333Mhz.

Now I have got some idea what really (O.C.) means from the specifications.

Thank you all for your guidance. Learnt a lot here.

 

[clutchc]

Thanks for the explanation. yes I get it now. I remember I installed a 400Mhz DDR1 RAM in my old Biostar AMD Socket A board that supported max 333Mhz and the inserted RAM was automatically down clocked to 333Mhz.

Now I have got some idea what really (O.C.) means from the specifications.

Thank you all for your guidance. Learnt a lot here.

Exactly. The "speed" of the ram you buy is simply the max speed the memory was tested/guaranteed to be stable at on the equipment used. The faster the ram you buy, the better it should perform at any given speed.

 

[clutchc]

I see the confusion in what i said or, what was missing. On newer systems, the ram can be over clocked, O.C.'ed, apart from the rest of the system. Back in the day, everything was O.C.'ed at same time.

That may have been because in order to OC the CPU (which had no unlocked clock multiplier) back then, one had to raise the base clock. And everything else that ran off the base clock OC'ed as well.