Lowered memory CL from CL16 to CL15, but is still at CL16

[RejZoR]

Since I don't think there is much point in overclocking 3600MHz RAM anywhere for Ryzen 5800X I've decided to lower the timings instead. And I went from 16-19-19-19-39-85 2T down to 15-18-18-18-35-58 using same voltage of 1.35. However, for some incredibly bizarre reason, the primary timing, CL doesn't want to go down. When I fire up CPU-Z and check the timings, it still says it's CL16. But in BIOS, it says CL15. What the hell? In 20+ years of doing this I've never encountered anything like this. Is this like a common thing that I'm somehow not aware or something? I'm pretty sure it wouldn't even post with CL14, but why it refuses to accept CL15 ?

[Mateyyy]

Perhaps you've got Gear Down Mode enabled in the BIOS?

[RejZoR]

4 minutes ago, Mateyyy said:

Perhaps you've got Gear Down Mode enabled in the BIOS?

It's in AUTO I believe which probably means ENABLED as default. But why it changes all other primary timings without any problems, but not CL ? I tried CL14 anyways and the thing didn't even boot, as expected. But with CL15 it boots, but shows CL16. I haven't had this Geardown thing before with X99 so I just left it as is.

 

What is this meant for anyway as it doesn't explain anything in BIOS itself. Is this like a power saving thing where it loosens up timings when not in heavy use or something? I still don't understand why other timings got changed, just not CL.

[Jurrunio]

Gear down mode only works with even numbers of CL, so it will raise up one tick if you use an odd number for it. It doesnt care abiut the rest.

[RejZoR]

Tried disabling it and system wouldn't boot even with CL16 anymore. From what I could gather on this feature is that it changes how DDR memory works on a clock cycle scale (low/high edges). Making me believe going all out on timings or MHz speed isn't all that helpful if this thing is meddling with DDR clock cycles just to make it work at any cost even if it would otherwise fail without this Geardown thing. Almost same "nonsense" as ECC memory on graphic cards. You can overclock them to 300 billion MHz and it'll just run, but it'll run like s**t. Is this the same thing and is really needed to validate timings and/or clock by running benchmarks and observe the scores? Coz now I'm running at 16-17-17-17, but given what I read, it's probably limping around running worse than at stock 16-19-19-19...

[Guest]

55 minutes ago, RejZoR said:

Tried disabling it and system wouldn't boot even with CL16 anymore. From what I could gather on this feature is that it changes how DDR memory works on a clock cycle scale (low/high edges). Making me believe going all out on timings or MHz speed isn't all that helpful if this thing is meddling with DDR clock cycles just to make it work at any cost even if it would otherwise fail without this Geardown thing. Almost same "nonsense" as ECC memory on graphic cards. You can overclock them to 300 billion MHz and it'll just run, but it'll run like s**t. Is this the same thing and is really needed to validate timings and/or clock by running benchmarks and observe the scores? Coz now I'm running at 16-17-17-17, but given what I read, it's probably limping around running worse than at stock 16-19-19-19...

More memory voltage.

 

Aim for efficiency during your testing.

Don't worry about having the same or better timings than everyone else.

 

Bandwidth can also improve performance over latency. (aiming for frequency. I.E. 3733mhz)

If you are battling to achieve 1ms better latency, you're going the wrong direction with the overclock.

[Jurrunio]

2 hours ago, RejZoR said:

this the same thing and is really needed to validate timings and/or clock by running benchmarks and observe the scores

You always verify with scores. That's all that matters

 

Also unless it's Samsung Bdie, tRP and tRAS have to be looser than 17 if you want to go faster

[RejZoR]

I've checked the RAM scaling and for 5800X it seems 3600-3733 MHz is the sweet spot where the gains are by far the highest. Lower or higher than that and scores and framerate in games is often lower. So, I'm just gonna aim at that. For the time being I'm just gonna run XMP profile which is 3600MHz and manually set it to 1T coz that usually helps a lot and generally works with any RAM without having to raise voltage. Tried 3733MHz with same voltage and same timings as 3600MHz and it seems to work fine, but I'll have to validate that to be really stable. In both cases fabric speed is 1800 MHz or 1866 MHz to be at 2:1 ratio which is also what's desired.

 

Checking CPU-Z benchmarks and this is also where I got the highest scores of 653 for single thread and 66000-ish for multicore. Trying to push timings lower actually caused scores to drop by as high as 50 for single core which was a huge drop.

 

I'm now thinking of trying GearDown thing to get it to OFF and still boot the system.