Intel benefit for fast memory at all folks?

[Zberg]

To those out there running intel z390 or later, are you seeing any benefit to very high memory (>3600mhz).  I ask because I have seen multiple test systems for the recent card launches at 4000mhz etc (on 10900k's).  Anyone have good info that there is a tangible benefit or is this one of those things that has severely diminishing returns (<5%)

 

 

[-rascal-]

12 minutes ago, Zberg said:

To those out there running intel z390 or later, are you seeing any benefit to very high memory (>3600mhz).  I ask because I have seen multiple test systems for the recent card launches at 4000mhz etc (on 10900k's).  Anyone have good info that there is a tangible benefit or is this one of those things that has severely diminishing returns (<5%)

 

 

 

Not really.. but .if you care about benchmark numbers...sure.

DDR4-3400 / 3600 is generally the sweet spot.

 

 

 

[DarkSmith2]

1 hour ago, Zberg said:

To those out there running intel z390 or later, are you seeing any benefit to very high memory (>3600mhz).  I ask because I have seen multiple test systems for the recent card launches at 4000mhz etc (on 10900k's).  Anyone have good info that there is a tangible benefit or is this one of those things that has severely diminishing returns (<5%)

 

 

All depends on the core clock of your CPU and application being used. 
If you have faster ram your CPU will become faster depending on how well the application you use it for can utilize cache.

 

If a CPU spends 50% of it's time waiting on ram, and you make the ram 50% faster then the CPU will become 1/(.5+.5*.5)= 1.333 times faster.

If it spends 10% of it's time waiting, then the speed up is 1/(.9+.1*.5)= 1.05 times faster.

The benefit is always positive, but depending how well the application can use cache, it may be large or small.

 

This is scientifically proven since 1988 and is called Gustafson's law. https://en.wikipedia.org/wiki/Gustafson's_law

 

This is Cinebench at 5.2GHz with 3600CL15 XMP:

 

This is the same OC with manual 4000cl17 ram OC and 200mhz more cache:

 

From what you can see at 5.2GHz you are indeed bandwidth limited with 3600mhz ram even in Cinebench. This equals more than 100mhz less core performance wise in Multithreading Cinebench score. So with 3600mhz kit you would lose as much performance as having more than 100mhz less core clock. while 3600mhz kits are probably quite enough for 5GHz, they are infact not for higher than that.

 

Digital Foundry partly explaining whats happening in their 8700k review. Long story short, "your CPU OC does nothing but wasting power without memory bandwidth to match it" 

 

[Guest]

Memory bandwidth increases nicely with Cpu core and cache overclocking. 

4000mhz is the minimum frequency I run with my 8700K and generally CL16-16-16

 

This screen shot is 5.2ghz, 5ghz cache and 4ghz memory.

GTX 480 running 3DMark IceStorm. 

I suppose the Physics score would be a representation of Cpu horse power + memory bandwidth in this screen shot.

 

https://www.3dmark.com/3dm/49342840?