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RAM not running at XMP speeds?

840 Views 9 Replies 6 Participants Last post by  ku4eto
Hey folks.

Using 5700X on a ASRock X470 Gaming K4, with Corsair LPX 3600 C18.

I have enabled the XMP profile and set the memory clock to 3600 Mhz.

I also fiddled a bit with the timings.

Original XMP is 18-22-22-42, tRC=84, 1T.
Currently, i am running it at 16-20-20-40, tRC = 80, 1T.

As seen from the screenshot below, the IF runs at 1800 Mhz, but DRAM frequency is ~1760Mhz, with the Bus speed being less than 100Mhz (97.5).

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· 49 Cans of Ravioli
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IF = RAM Speed, it's just a reporting difference in HWInfo. Look at CPU-Z, it's showing the right number.

100.0 BCLK * 18 DRAM multiplier = 1800mhz/DDR4-3600
97.5 BCLK * 18 DRAM multiplier = 1755mhz/DDR4-3510

there's nothing wrong, your BCLK is just dropping. if it bothers you, take the BCLK off auto and set it to 100 (or slightly over if it still droops) and/or disable Spread Spectrum
 

· Top kek
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Discussion Starter · #3 ·
IF = RAM Speed, it's just a reporting difference in HWInfo. Look at CPU-Z, it's showing the right number.

100.0 BCLK * 18 DRAM multiplier = 1800mhz/DDR4-3600
97.5 BCLK * 18 DRAM multiplier = 1755mhz/DDR4-3510

there's nothing wrong, your BCLK is just dropping. if it bothers you, take the BCLK off auto and set it to 100 (or slightly over if it still droops) and/or disable Spread Spectrum
Right, i will do that.
I thought it was as well false reporting, but 3 different monitoring tools show similar results - reported RAM speed being ~3520 Mhz.

Other than this, i know the Corsair LPX is low quality cheapo RAM. Does the current latency can be improved any further?
PC does not POST when using the CL16 XMP timings for 3200Mhz.
 

· 49 Cans of Ravioli
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Right, i will do that.
I thought it was as well false reporting, but 3 different monitoring tools show similar results - reported RAM speed being ~3520 Mhz.
HWInfo is just reporting FCLK/DRAM speed by assuming BLCK = 100 and using the DRAM multiplier to calculate from that. CPU-Z is multiplying the actual BCLK by the ratio.

3520 is the actual speed your RAM is running at and your FCLK is at 1760.
 

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Not to nitpick, but what you're getting is actually better than the XMP.

It looks like some AMD auto tuning feature?

I'd leave that as it is rather than trying to force the XMP settings.

Unless its an inaccurate reading, double check in CPU-Z
 

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try whit 2 T
my son's G,skill 2x32GB 4000MHZ wouldn't run xmp,until I set them to 2T,with his 5600x
 

· Top kek
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Discussion Starter · #8 · (Edited)
Not to nitpick, but what you're getting is actually better than the XMP.

It looks like some AMD auto tuning feature?

I'd leave that as it is rather than trying to force the XMP settings.

Unless its an inaccurate reading, double check in CPU-Z
Why it should be better than the XMP?

The XMP is 3600Mhz 18-22-22-42.
If i can get it at 3600Mhz 16-20-20-40, it should be better than 3510Mhz 16-20-20-40. Higher memory clocks = higher bandwidth, right?

Yes, its possible to be some Auto features from the motherboard, but not sure what exactly.


try whit 2 T
my son's G,skill 2x32GB 4000MHZ wouldn't run xmp,until I set them to 2T,with his 5600x
I think the performance difference between 3510/3600 Mhz and CR = 1T/2T would cancel each other out :|


HWInfo is just reporting FCLK/DRAM speed by assuming BLCK = 100 and using the DRAM multiplier to calculate from that. CPU-Z is multiplying the actual BCLK by the ratio.

3520 is the actual speed your RAM is running at and your FCLK is at 1760.
I set the BLCK to 100 and disable the Spread Spectrum.

Memory clock went from 1760 to 1770-1780 (its not static, hovers between 1770 and 1780 as values).


EDIT:
Turns out, its missreporting, due to how CPU-Z and HWInfo work.
AIDA64 complained something about virtualization enabled.

With SVM enabled, the reporting for BLCK and from there also the DRAM frequency gets skewed. Actual value is still 100Mhz for the BLCK, but the reported value is incorrect, due to the virtualization being enabled.
 

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Discussion Starter · #10 ·
Disabling spread spectrum in the BIOS may help bring your bus speed up a little.
I'm sure you can increase or OC your bus speed slightly to read 100 in windows. try 102 BCLK.
From my previous poste:

Turns out, its missreporting, due to how CPU-Z and HWInfo work.
AIDA64 complained something about virtualization enabled.

With SVM enabled, the reporting for BLCK and from there also the DRAM frequency gets skewed. Actual value is still 100Mhz for the BLCK, but the reported value is incorrect, due to the virtualization being enabled.
 
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