Help needed with 4266Mhz running at 3600Mhz (CMW16GX4M2K4266C19)

I have recently purchased a new gaming setup, which includes 16Gb (2x8) Corsair Vengeance Pro RGB 4266Mhz Memory (CMW16GX4M2K4266C19).

 

I have tried loading both XMP1 & XMP2 profiles in the motherboards UEFI/Bios (latest version - Hero XI), but can only get the memory stable at 3600Mhz in AIDA64 (about 99% stable that is).

 

I can work my way around the Bios fairly well and know how overclock the CPU, and to set voltages and stuff, but have no idea what to do with memory timings.

 

The memory will boot to windows from 2133Mhz all the way up to 4200Mhz, although the VCCIO and other CPU/Memory timer Voltages are high, at around 1.3v (which then slightly throttles the CPU). I have been able to bring these down again to a fairly low level, but the memory won't stay stable under a test any higher than 3600Mhz under any voltage the Bios has set, or that I have given it.

 

The Motherboard is compatible with memory all the way up to 4400Mhz from the Qualified Vendors List (QVL), and although this memory isn't on the QVL there is an identical 32GB kit on the QVL, that has the same serial number to this, apart from (so I was thinking) the numbers representing the DIMM capacity(32Gb/16Gb - 32GX/16GX?) and quantity amount (4/2 Modules - M4/M2?) - I have 16Gb (2x8) CMW16GX4M2K4266C19 compared to 32Gb (4x8) CMW32GX4M4K4266C19 on the QVL.

 

I knew it was a risk, but didn't expect to lose this much speed from those advertised at 4266Mhz, I was hoping least to hit the 4000Mhz mark. I'm thinking I may as well return them and and get the 3600Mhz 16Gb kit (listed on QVL) at around £230 less, unless there's a way to bring these stable close to advertised speeds.

 

If any one want's to show off some knowledge/skill's and help would be very much appreciated :laughing::withstupi and just to add, I have a pair of matching dummy modules installed with them (CMWLEKIT2), if that might be causing any issue.

 

thanks for looking/helping.

Edited December 5, 2019 by BIRKSY

You can spend 3 weeks trying to tune this out and hopefully it works. However, those are really loose timings at 4266 and I am not sure how well it tightens up at the next two rungs down. In comparison, a 3600C16 kit probably goes up to 4000 in easy, clear steps. Mine does on both my Code X and Formula XI. If you can find a 3600C16 kit for less (or something similar), that seems like a better plan than spending every remaining return window minute trying to force compliance. Also, unless you are a benchmark jockey, 3866 vs 4000 vs 4266 is not going to have any effect on your performance. On some kits I get the same results at 3733 than I do at 4000, with less voltage required. Those compatibility limits are not promises it will or should work. It means they enabled the setting in the BIOS. There are both diminishing returns and hard obstacles at the upper limit. Edited December 8, 2019 by c-attack
“Obsolesces”? Way to go predictive text.

Thank's for your input and advice. I have managed to get it stable at 3900Mhz and and I am currently 55 mins into a stress test at 4000Mhz so things are not to bad now.

 

I did get it almost stable at 4200Mhz but it wanted VCCIO at 1.44v and VCCSA at 1.3v+, which is way to much so I brought it back down to 4000mhz. VCCIO is now 1.248v and VCCSA at 1.184v which is way better and package/core temp's no higher than 88 degree's. (my Load Line Calibration (V-Droop) is at level 6 in Digi+)

 

I've not over clocked the CPU past 5.0Ghz all cores while doing this, but have managed to get the cache at 5.0Ghz with CPU at 1.355v, so a nice 1:1 ratio on the CPU & NB. The ram voltage at 4000mhz is 1.42v. I may try to push to 4100/4133, but I'm thinking it may take VCCIO back over 1.3v which is where I don't really want to be - possibly I've hit my "sweet spot" at 4000Mhz.

Yeah, I don't know why Asus IO/SA voltages default so high, even at much lower clocks. Even they admit its too high. I suppose it falls into the "make sure every PC boots" plan, but of course that doesn't always work so well with memory.

 

I wouldn't worry much about crossing the 1.40v line. DDR4 seems to take it well. I was amazed how cool my Dominators remained at 1.45 when I was pushing for 4266 this past Summer. Never broke 43C. I do think 4000 is the realistic limit for normal use for that chipset. I gave up on 4266 because it offered virtually nothing in return over 4000 while adding a much larger element of risk to stability. I think you can even make the the argument for 3733 vs 4000 on some configurations.

 

Side note on the cache: Check to see if you really are getting 5.0 on the cache/ring. My understanding is Asus will clock down the cache to -200 to -300 below the CPU clock limit on Z390. There is a setting to defeat it below the cache min/max, however it comes with a warning and the short research I did suggested it is in place for a good reason. I don't feel like you get much for your cache OC on the Lake CPUs like you might on a X99 series.

 

Glad you are doing better. Depending on what timings you had to use to get 4000 stable, you might still take a look at cost/value versus a 3600C16 kit, it is considerably less. Not sure if 3600C18 would be worth it.

Yeah as soon as I go past 3800Mhz the IO/SA wants to go higher, there at default otherwise (about 1.0v).

 

The ram voltage doesn't worry me, I've been up to 1.5v when testing 4200Mhz and only then hit 40 degree's C - I know they can do more than double that heat (heat sinks on ram are (mostly) superficial).

 

On the cache side of things, I'm with you on the thought of not sure how much benefit I'll see, and if it is a genuine 5.0Ghz like you say. Would have to do some checks/tests.

I have the the same ratio (1:1) on a 5960x with a Rampage V Edition 10 (X99) motherboard, CPU at 4.4Ghz all cores, but again the ram is a problem though, (32Gb Dominator Platinum) running at 2800Mhz instead of advertised XMP 3200Mhz (had 64Gb in originally but couldn't get past 2400Mhz).

 

I've hit 4000Mhz stable so I'm happy there, and not had to touch any timings (wouldn't know how) only voltages (and I'm currently tweaking voltages to get to 4133Mhz, had stable for about 10 min so far), so probably I'll just stick with what I have, even though the the price is tempting for the 3600 kits and 32Gb kits. I will check though how much performance difference ill get from 3600 to 4000/4133, if its not that significant I'd be a fool not to consider it more seriously.

I've returned the 4266Mhz and got the 4000Mhz from the QVL. Everything running as it should now with the XMP settings. The IO/SA were a bit high but managed to get them down, as well as the dimm voltage, so all good now.