Regarding this Intel have said this some time ago "Round Trip Latency Optimization optimizes the effectiveness of the memory by reducing the latency. However, on early DDR4 modules that had die problems, turning the option off allowed the module to be usable." you can read this here Re: NUC6i3SYH Random freezes
Now what these "early DDR4" means is unknown to me...
Probably it is better to leave unchecked on the HyperX due to the CL13 latency, the latency is already lower enough when the NUC use the automatic XMP profile of the HyperX!
However the most interesting thing if you want to try manually setup the memory timings options is that Intel removed the tRP option in the manual ram settings panel.
This setting was present in older models like the 5i3RYH but in the new NUC's there isn't anymore. This is the 3rd of (CL)-(tRCD)-(tRP)-(tRAS) that are the most common timings of a memory module (for example in the HyperX 13-13-13-33). And so you need it for manually set timings for a ram module.
Intel can you ear me? please add again this option, that has been removed, on the Visual Bios so it will be possible again to manually set also the tRP of memory module.
Hmmm… clear like many other statements from Intel at the moment
cvare said “…effectiveness of the memory by reducing the latency … turning the option off allowed the module to be usable.”
cvare also wrote “I misunderstood how the option worked.” and Intel changed from default ON to default OFF at 0039…
So I can speculate that they switched to default OFF to be more compatible with more ram-modules and it means if I have no problem with my RAM I should leave it ON (checked, selected) to avoid higher (because lower seems to be senseless) CL’s (instead of the e.g. 13 at the HyperX) or not , or how, or what ??????????????????????
The ram timings are read by the bios from the SPD/XMP of the memory itself in automatic (with HyperX the bios set in auto mode CL13) , then there is this add-on option that can force some parameters for timings:
ON = Lower latency (useless with HyperX that are already lower in automatic mode)
OFF = Normal latency (probably the best for HyperX that in automatic mode are already low)
so I think that OFF is better for them, following what they have said and what actually happens on the bios...
I hope it can help you
I tried to get a little bit more clear, but at cpu-z 1.75 I got at ON and OFF the same results like:
XMP timings table
CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
13.0-13-13-35-50-n.a @ 1067 MHz (1.200 Volts)
And at AIDA64 v5.60.3700 Cache & Menory Benchmark I got at ON
Read 30864 MB/s
Write 47214 MB/s
Copy 38561 MB/s
Latency 64.3 ns
and at OFF
Read 30524 MB/s
Write 46497 MB/s
Copy 34598 MB/s
Latency 64.2 ns
BUT at L1, L2 and L3 I also got a little bit different values, so I think it also doesn’t help to find out what will happen and what will be the better setting/setup…
So @Topix maybe you are right if you write
"ON = Lower latency (useless with HyperX that are already lower in automatic mode)"
because of the CL13… but then I don't understand why they changed at 0039 to OFF by default...
RTL is the length of time it takes for a signal to be sent to the memory plus the length of time it takes for an acknowledgment from memory of that signal to be received. The complete round trip time taken for a signal to be transmitted from point A to point B and then back to point A.
In BIOS setup, when RTL is enabled, it will minimize RT time to improve system performance.
In BIOS 42 implementation RTL is set to disabled by default.
I hope this helps,
"In BIOS 42 implementation RTL is set to disabled by default." NO, at 0039 yes, but at 0042 again (like before) enabled by default... which you can also read at the SY_0042_ReleaseNotes.pdf (Changed default value for Round Trip Latency to Enabled.)... and I have to say, I don't understand why before 39 enabled, at 39 disabled and at 42 again enabled... (I used every time enabled)
I think it was only Intel's trying during solving earlier problem with incompatible RAM modules....after some short time they decided that this option has no affect on system's behavior....it doesn't matter, it's only small option and user in real world cannot see some difference in system's speed....