#1 Make "Auto" values visible? by Vento 16.09.2016 13:12

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Hi, while I'm waiting some chips from china (Winbond chips compatiblity - Naming rules) I'm getting everything ready to mod my BIOS (Asus H97M-E motherboard). I'm planning a simple Intel AHCI/RAID ROM update (to v13.5.0.2164, should be the best choice for a H97 chipset right?) and a microcode upgrade/downgrade (explained better here: [Discussion] UBU Tool related Questions, Reports and Suggestions (182)), btw I 've another mad and maybe impossible "idea"... I do not know if this is even possible...

I'm not a rich guy, I got my PC parts from promotions, huge sales, friends and even a giveaway :D! Since my PC is not a beast I like to push it as much as I can. One of the funniest thing to do is to "OC" ram, I can't get past 1600 MHz, but I can tune tons and tons of timings! The only problem is that I'm missing some settings from the Asus "gaming" motherboard series, and some minor settings are quite kriptic... Let me explain.

First, as example inside the Maximus VII Gene bios there is a big chunk of settings missing (see attached image), I think that each settings is chipset dependent so there is no way to get them inside my board... right?

Second, some less important but still useful settings are located under "Skew Control" and "RTL IO-L Control", there is no official guide on the internet to tweaks these settings you just have to try an see if you get better or worse performance (or no POST at all hahah)...
One settings surprised me more than every other one, "RTL Initial value", currently set to "Auto" without any way to know which value will get after the POST, range from 1 to 63, I tried 1, 63, 32, 17, 33, 34, 35, 49 (after I surrendered) and get NO POST every time... Knowing which value the motherboard choose would be a nice start.

Other sub-menus have this problem, like "Skew Control" (huge impact on performance, no way to know which value I'll get with "Auto") and some other settings (images attached). So my final question is, is there a way to know show the value chosen for these settings like the other ones (with a simple square close to the input box)?

#2 RE: Make "Auto" values visible? by CodeRush 16.09.2016 13:22

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No. Auto means "select suitable value using a dedicated code path", not "some value we happen to call Auto". You can always reverse-engineer all DXE drivers related to this value to understand the code behind it, but it's much harder than poking the image with BCP/UBU/UEFITool/etc.

#3 RE: Make "Auto" values visible? by chinobino 17.09.2016 11:45

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RTL's are Round Trip Latency.

They should be left on Auto so that the motherboard can train the memory and POST successfully - they are not really for optimizing performance as Primary, Secondary and Tertiary timings are far more crucial.

If you are getting very bad bandwidth at high clocks speeds, sometimes it can be due to one memory channel or rank having a much higher RTL than then others, by which case you could attempt to correct it by setting it manually to a lower value that is closer to the others.

Sometimes a BIOS fix is issued to deal with bad RTL memory training issues for certain IC's.

One a Z170 motherboard RTL's can be set for each channel (A/B) and each DIMM rank (R0/1), not sure about Z97 though. [Edit] Just noticed your screen shot shows that it can.

You can download Asus Memtweakit here which *may* be able to read the RTL's in Windows.

When overclocking RAM the round trip latencies for each DIMM slot will increase (and may differ more) as you increase the clock frequency.

Generally, the DIMM slots closer to the CPU have shorter trace lengths and therefore lower latency and vice-versa.

Hope that helps.

#4 RE: Make "Auto" values visible? by Vento 17.09.2016 14:22

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Ty, any clue about the Skew Control Values?

#5 RE: Make "Auto" values visible? by chinobino 18.09.2016 09:53

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Zitat von Vento im Beitrag #4
Ty, any clue about the Skew Control Values?


These are much trickier to use and setting them wrong will result in a non-POST quite easily.

Raja from Asus is a pro at fine tuning RAM and uses MemTest Deluxe to test his results.

He has stated that "These settings are a bit cryptic on purpose."

You may glean some information about the Skew controls from Raja on this thread.

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