5820k - X99X - bugged XMP - need help with manual DRAM timings!

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galneon

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Mar 27, 2010
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I have an i7-5820k @ 4.2, Asrock X99X Killer, and a 32GB G.Skill 2800 MHz kit. It's rock solid with no BCLK/PCIE OC, cache at 3.3. For years now, I've had the RAM set to JEDEC #1 profile (2133 MHz, 15-15-15-35, 1.2v) and while I know it doesn't matter terribly with this particular chipset, I'd like to get it up to 2800, or at least 2666.

What happens when I apply the XMP profile is the BCLK is set to 127 and the ratio set to roughly match 2800. The problem is, none of the timings are set--they all stay at JEDEC #1 level, even the primary timings. For the primary timings, I can easily manually enter them, but I have no idea what to set the vast majority of the secondary and tertiary timings to. The XMP profile details provide tRFC, tRRD, tRRD_L, and tFAW, but that leaves another couple dozen parameters set to JEDEC and the guess work involved in scaling them up till I'm able to boot is enough to spin cycle my HDDs to death.

This is all the information I have to go on:

DSC_3377.JPG


Does anyone have any clue as to the manual settings I should try? They can be conservative. They can also be based on the extended specs of another similar DRAM. I just can't find the full specs of my modules. Should the BIOS extrapolate the missing timings from the primary timings I provide? Auto is not auto-adjusting them to the best of my reckoning. When I adjust only the timings revealed by XMP, the PC fails to boot. If it is actually adjusting the secondary/tertiary timings upon reboot (i.e. not in UEFI GUI upon settings the primaries), perhaps this is a red herring and the manually applied XMP settings are all I need--maybe more voltage is needed?
 
No luck with DRAM voltage up to 1.28v--that applies to 2666 as well... The secondary and tertiary timings, when set to auto, are NOT inferring values based on the primary timings after all it seems. I'm also wondering if the command rate should be 1T or 2T.

It would be really helpful if someone with a 16-16-16-36 set of DDR4 running at 2666 or 2800 could dump or screenshot their full timings (and voltage). I guess an X99 board would be ideal, but I would also be happy with values from a newer board.
 
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X99 does not respond to 2666+ without a BCLK change. If you have a manual OC set you might need to set it back to stock and get the dividers set up for your memory speed before you go about the CPU overclock. It will likely take some fiddling to get it to work. I ended up just going with 2400 on my old X99 setup because it has so much bandwidth anyways it doesn't matter much. G-skill doesn't list the sub-timings and many of the other settings that I know of for you to do it manually either.
 
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Had a problem with some Corsair RAM that wasn't stable at XMP settings (but was close, sort of...), and I just wound up RMA'ing, with the replacement set stable out of the box.

If you want to get higher, and XMP isn't behaving properly, you might contact GSkill and see what they have to say (I know they're not Corsair when it comes to RMA). Further, while bandwidth isn't an issue on X99, you might be able to increase performance with lower latencies, which are a product of memory speed and timings.
 
G.Skill support was worthless... They told me how to get the same XMP profile info in the screenshot above for manually entering the timings. Already had that obviously. They did tell me 2T command rate was required for 2800, but I guess that's obvious. I wonder how far down that extends--probably applies to 2666 too.

They don't have most secondary/tertiary timings in their spec apparently, or it isn't available to tech support or public. Ultimately I blame this on Asrock, though, as the board doesn't apply the XMP timings at all, and according to some of what I've read, most of the secondary/tertiary timings are figured by the motherboard at POST based on specified primary timings (and a few secondaries). This board, however, does not touch them even followed by a reboot when they are all set to auto.

I'll see if I can maintain the 2133 timings at 2400 without changing more than voltage--if I can't, I'll see if I can get timings down farther at 2133 instead. I can't be too upset about this set considering I got it for so much less than it sells today... The memory market is wild.
 
Not sure why XMP isn't setting the correct timings, are you on the latest bios?

When you run curtain ram speeds (2666, 2800, 3000) XMP sets the cpu strap to 125 for compatibility. Try setting the bclk to 125 instead of 127. If you'd rather use the 100 strap bump it down to 2400.
 
I will have to try BCLK 125 instead of 127 as a last ditch measure--tried everything else. After that I'll settle for a more modest clock. :p

Yep, latest BIOS... 3.10. Had the board since release and updated it the entire way. I initially had a 4x4GB set of G.Skill--rated at 2666 and stable there, and I recall the board setting XMP no problem and not even having to do any CPU OC tweaks after applying it (I ran it at 4.4 back then).
 
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