Question Bus speed and ram bandwidth

kanewolf

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https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=189125,198019

I'm comparing the 10900x and 9940x.

The 10900x has a higher memory bandwidth, does this matter using 2400 ram?

The 10900x also says DMI3 on the bus speed, but the 9940x has a higher bus frequency, and they both have the same cache size. Does that mean the 9940x has better bus?
The difference in RAM bandwidth is what the two CPUs were tested with. The 10900 shows 2933 RAM support the 9940 only supports 2666 -- officially.
With your 2400 RAM, the RAM bandwidth will be the same for the two CPUs. And to maximize the RAM bandwidth, you have to have four matching DIMMs. If you only have two DIMMs, then your RAM bandwidth will be 1/2.
 

sodium.in.toilet

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The difference in RAM bandwidth is what the two CPUs were tested with. The 10900 shows 2933 RAM support the 9940 only supports 2666 -- officially.
With your 2400 RAM, the RAM bandwidth will be the same for the two CPUs. And to maximize the RAM bandwidth, you have to have four matching DIMMs. If you only have two DIMMs, then your RAM bandwidth will be 1/2.
I already know what you're talking about. I was asking about 85 GB/s and 94 GB/s. I have no idea what that speed is for but it says memory bandwidth.

I'm already using 4 of the same ram sticks in dual channel so I'm good there.
 

kanewolf

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I already know what you're talking about. I was asking about 85 GB/s and 94 GB/s. I have no idea what that speed is for but it says memory bandwidth.

I'm already using 4 of the same ram sticks in dual channel so I'm good there.
What about the 85GB/s or 94GB/s -- With 2933 RAM and 4 DIMMs the maximum memory bandwidth for the 10900 CPU is 94GB/s written or read from RAM.
With 2666 RAM the 9940 has 85GB/s maximum RAM performance.
The number is just a number to use for relative comparison. The 10900 will be able to read or write to main memory about 10% faster than the 9940 IF you are using the faster RAM. Both CPUs using the same RAM will perform the same.
 
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sodium.in.toilet

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What about the 85GB/s or 94GB/s -- With 2933 RAM and 4 DIMMs the maximum memory bandwidth for the 10900 CPU is 94GB/s written or read from RAM.
With 2666 RAM the 9940 has 85GB/s maximum RAM performance.
The number is just a number to use for relative comparison. The 10900 will be able to read or write to main memory about 10% faster than the 9940 IF you are using the faster RAM. Both CPUs using the same RAM will perform the same.
Thank you that makes more sense.

So for high speed memory, XMP increases the max memory bandwidth and the frequency?

I'm told that 2400 is low for x299.
 

kanewolf

Titan
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Thank you that makes more sense.

So for high speed memory, XMP increases the max memory bandwidth and the frequency?

I'm told that 2400 is low for x299.
It MIGHT improve performance. It will depend on the software. If it uses a lot of memory (database) then you will get better performance. Games may have small changes. It will depend on the rest of the hardware, the resolution, etc.
You have not described what this system is doing so there is no way to answer.
 

sodium.in.toilet

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It MIGHT improve performance. It will depend on the software. If it uses a lot of memory (database) then you will get better performance. Games may have small changes. It will depend on the rest of the hardware, the resolution, etc.
You have not described what this system is doing so there is no way to answer.
All purpose pc, but gaming mostly. I believe jays2cents on youtube tested all that and found 3000mhz to be the limit for usefulness. I'm not sure about timings though. My ram is 2400 CL17 which was budget ram 3 years ago and I paid $200 for 24gb. Thinking about selling it and buying new faster ram.
 

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