A8-3850 & ga-a75m-udh2 & f3-14900cl9d-4gbxl

[PhoxxLoTekk]

Hi G.Skill Tech,

I have put together the following AMD-based system:

- CPU: AMD A8-3850
- MB: Gigabyte GA-A75M-UDH2 (BIOS version F2 as far as I can tell)
- MEM: G.Skill RipJaws-X DIMM Kit 4GB PC3-14900U CL9-9-9-24 (F3-14900CL9D-4GBXL)

Following the manual I installed the two memory modules in
the slots DDR3_1 and DDR3_2 for dual channel configuration.

The BIOS sets the DDR3 frequency to 1600MHz instead of 1866MHz.

The timings are automatically set as follows (for 1600MHz):


List of all settings | SPD | Auto |
------------------------------------------------------
1T/2T Command Timing | -- | -- |
CAS# Latency | 9T | 9T |
RAS to CAS R/W Delay | 9T | 9T |
Row Precharge Time | 9T | 9T |
Minimum RAS Active Time | 28T | 28T |
TwTr Comand Delay | 6T | 6T |
Trfc0 for DIMM1, DIMM3 | -- | -- |
Trfc1 for DIMM2, DIMM4 | 110ns | 110ns |
Write Recovery Time | 12T | 12T |
Precharge Time | 6T | 6T |
Row Cycle Time | 37T | 37T |
RAS to RAS Delay | 5T | 5T |
Four Bank Active Window | -- | -- |

Bank Interleaving : Enabled


When changing to 1866MHz, the displayed SPD values stay
the same, but the Auto values change to slower timings
such as 11-11-11-32 and so on.

According to your post, AMD users have to manually
adjust the timings to run the G.Skill RAM at the
speed it is actually capable of.

So my question is: Could you please tell me for each
of the settings in the list above what value to set,
especially the missing ones such as "1T/2T Command Timing"?


Cheers,
Phoxx.

[GSKILL TECH]

Set DRAM Frequency to DDR3-1866

DRAM Voltage 1.50V

1T/2T Command Timing | 2T | 2T |
CAS# Latency | 9T | 9T |
RAS to CAS R/W Delay | 10T | 10T |
Row Precharge Time | 9T | 9T |
Minimum RAS Active Time | 28T | 28T |
TwTr Comand Delay | 6T | 6T |
Trfc0 for DIMM1, DIMM3 | -- | -- |
Trfc1 for DIMM2, DIMM4 | 110ns | 110ns |
Write Recovery Time | 12T | 12T |
Precharge Time | 6T | 6T |
Row Cycle Time | 37T | 37T |
RAS to RAS Delay | 5T | 5T |
Four Bank Active Window | -- | -- |

Someone also posted a thread about this in the DDR3 BIOS Configuration guide section, so you can take a look at their experience.

Thank you
GSKILL TECH

[PhoxxLoTekk]

Hi again,

thanks for your quick response!

I have seen the post in the DDR3 BIOS Configuration guide section.
One guy has the same CPU and board as I, but different RAM

His:
F3-14900CL9D-8GBXL | 2x4GB | 9-10-9-28-2N

Mine:
F3-14900CL9D-4GBXL | 2x2GB | 9-9-9-24-2N

That's why I didn't just copy&paste his values. Maybe I'm wrong,
but your answer seems to be based on his 9-10-9-28 timings.

My initial approach was to set 2T and 9-9-9-24 for the first five
values of the timings table I posted and just leave the remaining
timings as they are. The two things that let me think that it's not
that straigtforward are

(1) that the alleged SPD timings are 9-9-9-28 instead of 9-9-9-24,
which makes me wonder if the SPD was read correctly (especially
the remaining eight timing values)

(2) some values obviously aren't stored in SPD, but I have to
set them to some value when setting timings manually

The ideal case would be if G.Skill has some PDF file for each memory kit
with tables showing all the timings for 1333/1600/1866MHz that one can
safely copy & paste - do these exist (for download)?


Cheers,
Phoxx.

[Tradesman]

Many of the advanced timings are done automatically by the BIOS based on the spec timings of the stick and vary from mobo to mobo and even on the same mobo with different versions of BIOS so there is no universal set of Advanced timings. Also, tolerance levels between mobos of the same model and BIOS can have an effect i.e. some can run a CR or 1T while others require 2T

[GSKILL TECH]

You don't need it, the timings and settings you need are all on the memory. All you need to do is input those in BIOS. It is straight forward. The other guy post his experience, but doesn't mean you copy everythign exactly the same. He's just giving you an idea of what you need to do to be stable, but you should be inputting settings for YOUR memory.

Read and apply, not read and duplicate.

Thank you
GSKILL TECH

[PhoxxLoTekk]

I've found the most easy and straightforward solution and posted it in the
DDR3 BIOS Configuration guide section.

Cheers,
Phoxx.

[Tradesman]

Thanks for sharing the info