Some questions about RAM speeds and CL

[Rxd]

1) What are the lowest timings for 3000, 3200 and 3600 memory kits?

2) Currently looking into 2 kits for a 3700x build 3200 c16 and 3600 c18. Which one is better? (prices are almost the same)

3)Why Linus hates XMP? And what is his solution to using the advertised speeds if not with XMP?

[porina]

2, 3600C18 is both faster and lower latency than the 3200C16 so would be my choice assuming it is compatible with your system.

3, Don't know about Linus, but basically compatibility of high speed ram through XMP is far from 100%. This is basically a ram manufacturer overclock and timings are not standard defined. Best compatibility seems to be if you buy modules released for the CPU you are using. For example, there were changes to preferred timings between Skylake and Coffee Lake, and Ryzen Zen+ to Zen 2 is different again. That would reduce the risk. Manufacturers don't always state what they optimised for, in which case you can try to guess from when the modules were released. This is complicated further they often sell them under the same name with different revisions and behaviour characteristics. For lower speed kits (<3000) it doesn't matter much, but above that it starts to get hit and miss.

[boey]

15 minutes ago, Rxd said:

3)Why Linus hates XMP? And what is his solution to using the advertised speeds if not with XMP?

XMP doesn't work 100% of the time. Usually what I've seen from his videos is that he manually overclocks the memory to the advertised speeds, and if it doesn't work then he tones down the speed, increases timings or just doesnt enable xmp at all.

[alatron978]

1) 3000 14-14-14-34   3200 14-14-14-34   3600 15-15-15-35
2) 3600

3) Because it doesn't always work.

[Rxd]

@porina How exactly is C18 lower than C16?

[porina]

30 minutes ago, Rxd said:

@porina How exactly is C18 lower than C16?

In short, it is given in number of cycles. Faster ram allows each cycle to be shorter, so the actual total time is reduced.

 

Actually I made a mistake there. They're the same latency now I actually plug it into a calculator. 18/3600 = 16/3200.

[Rxd]

@porina All good, so it doesn't matter which kit I pick?

[porina]

41 minutes ago, Rxd said:

@porina All good, so it doesn't matter which kit I pick?

Given the latency in time is the same, I'd go for the faster kit.

[nick name]

If you wanna spend more money then there are better kits to be had.  

[SenKa]

Faster speed and lower "CL"/Timings is better, thats the simple rule. Mind you, there are diminishing returns past a certain point, but faster is by and large better if your CPU can run it.

 

The reason Linux hates XMP is simply because it doesn't work most of the time, especially if your particular kit hates voltage, as XMP tends to crank volts pretty hard. I have a GSKill kit that actually got less stable with even minor voltage changes, even when everything points to voltage being the reason for not being able to OC further.

 

Also, Samsung DRAM is regarded as better than SK Hynix, but it comes at a cost premium.

[joe123.]

You can see the differences here:

 

http://maxxpi2.de/pages/results/overalltop15.php