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Resolved Question

Install RAM with higher speed than CPU support

Jun 19, 2016 9:14AM PDT

What happens if I install RAM with higher speed than the speed CPU can support, provided the motherboard can recognize and run the RAM at full speed? I looked for the answer on many sites but failed to find what I want to know.
Suppose that the CPU can support 1600 RAM, and 2133 RAM is installed which mainboard can recognize and run at full speed without changing anything in BIOS.
- Some said the motherboard will adjust the timings for other components to match the frequency of the 2133 RAM. In this case, it will automatically OC (.......). If so, how can I see the change since CPU-Z doesn't show any change in CPU?
- Some said the motherboard will only run at what the CPU can support in spite of recognizing the RAM and showing the correct speed in CPU-Z.
In both cases, the only thing change in CPU-Z is the memory and SPD tabs. What happens exactly and how can I tell? How about integrated graphic processor? Does it have any effect, and how can I tell?

As I was so confused to read different answers, I decided to ask. I'm sorry if this is a basic question that I should know.

PS: I know that normal use doesn't see the difference.

Discussion is locked

TangNgoc01 has chosen the best answer to their question. View answer

Best Answer

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I've seen this question many times.
Jun 19, 2016 9:26AM PDT

There is no correct answer since the result changes with the motherboard, CPU and version BIOS.

There is usually a single digit overall speed gain so you find folk chasing higher memory speeds with little to show in the results.

If I wade through your post I think this is your question:
"how can I see the change since CPU-Z doesn't show any change in CPU?"

You would run a benchmark program.

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Benchmark only
Jun 19, 2016 9:35AM PDT

Thanks for your answer. I read many posts online, but by the time I got close to the answer, people stopped discussing. Back to the topic, running benchmark software is the only way to know if any thing is changed, isn't it? What kind of benchmark should I run, and what should I look for?
Thanks again.

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That was my finding too.
Jun 19, 2016 9:45AM PDT

There are now so many benchmark programs and up top I can't tell if it's Windows, Linux, DOS or such so find those that measure memory speed alone.

And I'll repeat myself. This is usually a sub-percent change in system speed. That is, from boot to desktop showing might only change it by a split second. Be sure you know this going in.

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Testing RAM
Jun 19, 2016 9:56AM PDT

Sure. I know it definitely (as I said in my original post).
If I test and confirm that the RAM runs at the speed about that for 2133 RAM (say by Prime95), does it mean any change in CPU? How can the motherboard adjust the timing for the CPU to work? Does it automatically OC the BCLK or something else to sync with the RAM frequency? Or what does it do? Do users have to OC the CPU manually?
How about integrated graphic processor?
This is the part I'm looking for in many discussions. They stopped just before what I really want to know.
Thank you very much.

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Let me carve out the question.
Jun 19, 2016 10:14AM PDT

You are surrounding the question with other text that I may get it wrong.

And before I start, the memory speed depends on the system design which could be a current gen Intel where the memory controller is on the CPU or an older design where it was on another chipset. I can't fit a course into the PC board design from say 8088 to present day so with that clear.

You also have 3 or more questions here. There is no correct answer since we would have to know exactly which board, CPU and then it could change with the BIOS.

This is why I will not be able to answer these questions here.

No one but the engineers that created the board you are doing this on can get down into the depths here and then a different BIOS and those answers are toast.

So, in short, test with benchmarks.

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I really have not look closely on my latest bulit but...
Jun 19, 2016 10:33PM PDT

I remember way back I try to set a higher speed on the RAM than what the cpu calls for, and in this case, the CPU won. It drop the RAM speed. Ever since I have not try that again. If you think you can go higher, then go for it. It won't hurt anything.

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Jun 20, 2016 5:17AM PDT

For newer stuff that has native support for 1600 ram and you want to run 2133 ram you must increase the ram bus speed.....OC.

You can do that manually or use that xmp profile stuff.

This will have limited impact on cpu perf.

Where this will show is a ram intense app such as gaming with a igp.

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Back to square one
Jun 20, 2016 9:00AM PDT

Thank you very much for your answers. My friend just tried it in his laptop Clevo W230ST with Prema Bios. He was able to put 2133 RAM in without using XMP although his CPU i7-4700mq officially supports RAM up to 1600 MT/s. All he did was installing new RAM. The CPU-Z shows exactly what RAM he is running; Prime95 confirms what his RAM is actually running. However, I feel like it's a separate component because nothing in the CPU has changed, so I REALLY want to know if the mainboard changes something to adapt the new RAM, what it is?

In the CPU tab:
Core Speed: 800; Multiplier: x8 (8 - 34); Bus Speed: 100

In the Memory tab:
DRAM Frequency: 1066; FSB:DRAM: 1:8.

I think I'm back to square one. Thanks anyway.

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And how did you account for ???
Jun 20, 2016 9:22AM PDT

DRAM was clocking data on one edge of the clock so way back when we saw the move to DDRAM (you can google each acronym) where data was clocked out on both the rising and falling edge of the close so at 1066 data clock rate the data was moving at 2132 (or 2133 depending on your take on the math.)

The CPU speed and it's clock rates were decoupled about a decade ago so I'll start and stop on that item here.

You are chasing small gains here. From your posts you are mixing all those numbers together without a background on PC designs from the IBM 8088 to present day. Even I would be pressed to cover them all but here, it looks to me that you have a working system that's performing well.

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Jun 20, 2016 10:17AM PDT

Put a stick of 1600 ram in your machine and run a ram speed test.

Now put a stick of 2133 ram in your machine and run a ram speed test.

If the MB/s goes up for the 2133 it says the machine is auto adjusting and the ram is working fine.

This has nothing to do with cpu speed that's a different area.