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lambdapro2
2 Iron

XPS 8700, DDR3L-1866 RAM Upgrade

I just upgraded my XPS 8700 RAM from 16 GB Hynix DDR3L-1600 to 32GB Crucial DDR3L-1866.

Performance improved based on userbenchmark, i7-4790K, OC2

23 GB/S Multicore vs 20.2

21.6 GB/S Singlecore vs 20.6

59 ns latency vs 61.1

Has anyone else tried 1866 vs 1600?

David

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3 Replies
7 Thorium

Re: XPS 8700, DDR3L-1866 RAM Upgrade

Your improved stats are probably more likely due to doubling the amount of RAM that's installed.

The 1866 MHz RAM is likely running at 1600 MHz because that's controlled by BIOS and the chipset. The specs for the XPS 8700 say RAM "up to 1600 MHz".

Faster RAM will simply clock down to the lower "allowed" limit.

Ron

   Forum Member since 2004
   I am not a Dell employee

7 Thorium

Re: XPS 8700, DDR3L-1866 RAM Upgrade

Ram FSB is based on the cpu not the model or chipset.

https://www.crucial.com/usa/en/advisor

Adding faster ram DOES NOT make the system run faster.

For example CORE i3-2120 has 3.3GHz CPU clock and a bus/core ratio of 33.

This means that the FSB base-clock is 3.3GHz/33 = 100Mhz.
Since FSBs are quad-pumped, we can just look at it as 100*4MT/s = 400MT/s

The Intel QuickPath Interconnect (QPI) replaced the front-side bus (FSB) in platforms starting in 2008

All of this is marketing so that you can't tell how fast something is really running.

Although some high-end Core i7 processors expose QPI, other "mainstream" desktop processors do not They are intended for single-socket boards (e.g. LCore i3, Core i5, and other Core i7 processors do not expose QPI externally, because these processors are not intended to participate in multi-socket systems. QPI operates at a clock rate of 2.4 GHz, 2.93 GHz, 3.2 GHz, 4.0 GHz or 4.8 GHz (4.0 GHz frequency is introduced with the Sandy Bridge-E/EP platform and 4.8 GHz with the Haswell-E/EP platform).

Only the K models that are UNLOCKED allow you to adjust the FSB. 

They keep adding wait states as well so Ram Speed is relative.

https://www.youtube.com/watch?v=D_Yt4vSZKVk&


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lambdapro2
2 Iron

Re: XPS 8700, DDR3L-1866 RAM Upgrade

I just now tried the benchmark with two sticks of 8 GB 1866 RAM and it ran the same speed as 4 sticks of 8 GB 1866 RAM.  I think that it is running at 1600, but I think that it is just faster RAM.  So I am running faster than the DELL RAM that came with the system.

Crucial DDR3L 1866 8GB sticks vs Dell (Hynix) 1600 5 GB sticks.

David

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