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Level 10
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Level 10

I am stuck at 55 41 78 or 3E POST CODE

Encountered this a lot,usually:
3E means too low Write Recovery / read to precharge time
78 means too tight TRCD/TRP
41 Means you went too tight on tertiary or you pushed too much voltage on Hynix MFR
55 well this means a lot,from not enough voltage for give settings,too tight TRFC ,improper tertiary.


General behavior of various IC

Hynix MFR is the classic of X99 and actually the WORST performer on AIR . It has many problems on AIR,meaning hard to get high frequency and tight CAS . Worst voltage tolerant IC , creates many problems like you can pass DDR4-3200 12-15-15 at 1.58 V, 1.54V gives can?t train 55 and 1.62V gives you 41 because the voltage is too high . The best sticks to look for are the ones that support higher voltages at higher speeds , good sticks can bench DDR4-3200 12-15-15 under 1.6V and with good voltage tolerance they might get you to DDR4-3333 12 +

Hynix AFR is the improved die from Hynix . Fixes many of MFR flaws and it?s a huge improvement . Can tolerate high voltage at high speeds and run great on X99 and Z170 . They will be available very soon on Kingston HyperX memory and other vendors will implement too for sure.

Typical benching scenarios are
DDR4-3600 12-17-17 at 1.65
DDR4-3733 12-18-18 at 1.75
DDR4-3866 13-18-18 @1.85
DDR4-4000 13-19-19@1.94

Of course voltage might vary and be aware they are harder to clock compared to Samsung,my few sticks can?t manage over DDR4-3733 on any board but Impact ( 1 dimm per channel board)

Samsung D-Die K4A4G085WD

First die from Samsung has good voltage tolerance and can be found on a lots of modules from different vendors from Gskill 3000,3200 Ripjaws,early 3466 and 3600 Ripjaws-V and Trident-z to Corsair lineup and so on . Can go up to 2-2.1V on air and scaling is linear .
Typical benching scenarios are at DDR4-3733 15-19-19 for worser kits with 1.8-1.9V to better sticks doing even 13-18-18 .

Samsung E-DIE K4A4G085WE

Second revision from Samsung gained huge improvements . Voltage tolerance is great,taking up to 2.1V at 4200+ speeds ,trcd limits have gone lower and overall it looks like a very solid IC.
Typical benching scenarios are:
DDR4-3600 11-17-17 at 1.9V and under
DDR4-3866 11-19-19 at 2.05V and under
DDR4 -4000 12-20-20 at 2V and under

So far to be found on G.skill Trident-Z and Ripjaws-V kits on week 38 and higher , Teamgroup inferior bin of 3866 18-22-22 and newly Corsair 4000c19 .
The best modules to aim for are low TRCD ones, generally aim for DDR4-3600 TRCD/TRP 17 and DDR4-4000 TRCD/TRP 19 . They are the easiest to clock modules and also can go lower in tertiary/secondary ,TRFC of 280 at 4200 speed should not be a problem for good sticks.


2 DIMM vs 4 DIMM

4 DIMM is ALWAYS faster than 2 DIMM at similar clocks/timings . Early results in XTU benchmark showed that , however this puts more stress on IMC and result in looser timings sometimes. The only timing to be adjusted is TWRWR_DD which has to be 8 otherwise platform will not start.
Keeping identical secondary/tert timings at same clock speed on 4 ghz 32M test this is about 1 second faster at DDR4-3466 C12 which is quite a difference in 32M world.

Please NOTE that AUTO RTL/IOL on 4 DIMM scanarios will give you very loose IOL,this is because Maximus boards will automatically set IOL_latency offset 15 instead of default 21 when 2 dimms are used. Easy way to fix this is to manually set 21 for better performance.


BAD RTL Training

Sometimes the memory training is missed and you can see big difference in RTL/IO,for example instead of 50/51/7/6 you will have 58/51/14/6 and similar.This WILL hurt the performance a lot in 32M and XTU too,It is always best when finding proper RTL/IOL combo to manually lock them by overriding AUTO so you will have same values every time.

Example : Samsung D 3733 C14 normal RTL vs fail RTL :


The TWRWR_DR and TWRWR_DR timings .

Being advocated to go as low as it can this is actually a big lie as tested on all ic available I had found that going lower actually hurts and optimum value for high and medium speeds is actually 8 .
Tested on MFR,Samsung E-die and Kingston AFR,4 4 is worser than 8 8 period .
AFR DDR4-3866 13-18-18


0.400 Sec Worse
E-DIE DDR4-4133 12-20-20 TWRWR_DR TWRWR_DD 8 8


0.300 Sec Worse
Hynix MFR DDR4-3200 12-15-15 TWRWR_DR TWRWR_DD 9 9 same as 8 8 result


1 SECOND Difference at slower times !


Actually encountered this issue when I left this timing on AUTO and went from DDR4 3466 C12 to C11 and got a worser score !. After a few tries I found that AUTO gave me 6 6 and after lowering this to 5-5 performance gain was normal . It actually can go lower to 4 4 and 3 3 but performance was similar to 5-5 on Hynix AFR and worser on Samsung E-die and stability was a little bit worse so I would recommend 5-5 in all cases period.


Hynix AFR DDR4-3466 C12 Twrrd_dr , dd at 5 5 : 7 26 110

DDR4-3466 C11 TWRRD_dr dd at 6 6 7 26 281

DDR4-3466 C11 TWRRD_dr dd at 5 5 : 7 m 25 672

Samsung E-die 4133 12-20-20 TWRRD_dr dd 4 4 : 7.23.719

Samsung E-die 4133 12-20-20 TWRRD_dr dd 5 5 : 7.23.562



General rule is that they go tighter with CAS going lower and they are linked with Write to Read Delay L and S . Write to Read Delay L and S can go lower than 6 even to 1 but show no performance increase whatsoever,except when lowering them by TWRRD_SG and TWRRD_DG.

For example the settings pictured above resulted in showing 7 7 for write to read delay L and S although they were set at 6 in UEFI .

Lowering TWRRD_DG from 22 to 18 resulted in showing 7 and 3 :

The performance boost is little but might matter on

Since we are talking about Write to Read Delay(not L and S), this timing can go as low as 1 and see little performance boost


TRDRD_dr and TRDRD_dd

This is actually interesting because of conflicting results.While testing IC from Hynix and Samsung I noticed that Hynix prefers this two timings at 0 0 gaining almost half a second boost while Samsung prefers the other way around having the best results at 5 6 .Even complementary values like 4-5 5-5 6-7 gave worser results so my findings are that if you own a Samsung based memory this have to be set at 5-6 while Hynix likes them at 0-0.

Example :

Samsung D-Die 3733 14-19-19
TRDRD_dr + dd 0-0  7.26.172

TRDRD_dr+dd 4-5  7.26.000

TRDRD_dr+dd 5-6  7.25.844

Hynix AFR 3866 13-18-18
TRDRD_dr+ dd 5-6  7.24.172

TRDRD_dr+dd 0-0  7.23.969