GIGABYTE GA-990XA-UD3 - how populate dual channel slots with different sticks?

[ZdendaV]

I have a GIGABYTE GA-990XA-UD3 MoBo 1.x revision with a AMD Phenom II X4 955 C3 revision CPU and Corsair XMS3 DDR3 8GB 2000MHz CL9 (2x4GB) CMX8GX3M2A2000C9 in slots DDR3_1 and DDR3_2, memory set to Unganged mode.

I have ordered Crucial Ballistix Tactical DDR3 16GB 1866MHz (2x8GB) BLT2CP8G3D1869DT1TX0CEU for an upgrade.

The question is how to populate the slots?

I have read the Phenom has 2 independent memory controllers, each capable to use different memory timings.

That would suggest to put always the same modules on one channel but then one channel would have 8GB of RAM and the second 16GB of RAM - is that a problem?

Or the the obvious second choice - populate each channel with a Crucial and a Corsair module.

In that case both channels have the same amount of memory but consisting of two different modules - is that a better choice?

[AgentFXA]

Is that a problem?

you'll likely run into ram latency problems using different ram brands and depending on how you intermix it. You'll probably end up at 1333 speed and if you're lucky it is stable. Meh, whatever mix route you choose you won't be a winner.

Old Pheno can do 1600 max as far as I recall and 1866 is for FX CPUs

[ZdendaV]

First, thank you for your answer.

I have no problem, when the memory system runs at lower speeds, if it is stable.
I'm buying (unnecessary) fast RAMs to have some headroom.
Actually I'm running the Corsiar sticks in slots DDR_3_1 and DDR_3_2 as recommended in the manual, all set to Auto in BIOS and the memory runs at 1066.
I'm not overclocking at the moment. I was overclocking but it wasn't worth it - to be specific it wasn't worth to run the memory at higher speeds (and I don't want to stress the sensitive Phenom II memory controller).
If the I'll manage to run all 4 sticks at 1066 stable, I'll be satisfied.

So the question is - in what combination there is a higher chance to run all four sticks stable?

Corsiar in DDR_3_4, DDR_3_2 and Crucial in DDR_3_3, DDR_3_1
or
Corsiar in DDR_3_4, DDR_3_3 and Crucial in DDR_3_2, DDR_3_1

[AgentFXA]

Do the Ballistix (16GB) in slot 1/2 and the Corsair (8GB) last and see how it fairs - should be the best option. Just leave ram timing all on auto hence the mobo can adjust as needed.

[ZdendaV]

Thanks.
I'll try as suggested (Crucial in DDR_3_4, DDR_3_2 and Corsiar in DDR_3_3, DDR_3_1), when the Ballistix arrive (Monday or Tuesday) and report back.

[ZdendaV]

Done and everything is looking good.
Now I'm running Memtest (2nd pass), all looking good so far ...
The Corsairs are in slots DDR_3_4 and DDR_3_2 and the Ballistix in slots DDR_3_3 and DDR_3_1,

[AgentFXA]

Great, but what is your actual ram speed now?

[ZdendaV]

The same as before 1066 (timing too).

[AgentFXA]

Happy with that, fine?!

Keep in mind IF you ever want full throttle just remove the Corsairs and speed should go up to a solid 1866 for the Ballistixs - not sure what for you need 24GB ram as 16 is already more than plenty. I even have a 2GB ramdrive for the user/system temp folders and still 10GB unused.

bye

[ZdendaV]

Yes, I'm very happy 

Why should the Corsairs brake the Ballistix?
In theory the Corsairs should be faster than the Ballistics (2000 vs 1866).
Am I missing something?

Because no RAM/SSD/HDD is big enough and games love plenty of RAM.

[AgentFXA]

Yes, when mixing different ram speeds the slower ram set is setting the clock! (would be 1866/2 in your case)
When mixing brands too the speed further falls down due to (brand) latency sync issues.

Your 1066 (dunno exactly what this is) seems to indicate you're nowhere near what you ram can do!?



 

[ZdendaV]

Then the Ballistix is the slower one.
The timing in the SPDs seemed almost the same for the Ballistics and the Corsairs.

1066 means the memory runs at 533MHz DDR.
I have no idea why the Mobo chooses such a low frequency, when the memory is set to auto.

Sure the RAM can do more.
But is the same true for the memory controllers in the Phenom II ?

I'll post more details in the evening ...

[ZdendaV]

Here are some details:
BIOS F13 (latest non Beta BIOS)

Actual memory timing

Memory Frequency      536.8 MHz (3:8 )
CAS# latency (CL)      7.0
RAS# to CAS# delay (tRCD)   7
RAS# Precharge (tRP)      7
Cycle Time (tRAS)      20
Bank Cycle Time (tRC)      27
Command Rate (CR)      1T

Corsair XMS3 DDR3 8GB 2000MHz CL9 (2x4GB) CMX8GX3M2A2000C9
   SMBus address      0x50
   Memory type      DDR3
   Module format      UDIMM
   Manufacturer (ID)   Corsair (7F7F9E00000000000000)
   Size         4096 MBytes
   Max bandwidth      PC3-8500F (533 MHz)
   Part number      CMX8GX3M2A2000C9 
   Number of banks      8
   Nominal Voltage      1.50 Volts
   EPP         no
   XMP         yes
   XMP revision      1.2
   AMP         no
JEDEC timings table      CL-tRCD-tRP-tRAS-tRC @ frequency
   JEDEC #1      6.0-6-6-18-24 @ 457 MHz
   JEDEC #2      7.0-7-7-20-27 @ 533 MHz
   JEDEC #3      8.0-7-7-20-27 @ 533 MHz
   JEDEC #4      9.0-7-7-20-27 @ 533 MHz
XMP profile         XMP-2000
   Specification      PC3-16000
   Voltage level      1.650 Volts
   Min Cycle time      1.000 ns (1000 MHz)
   Max CL         9.0
   Min tRP         9.00 ns
   Min tRCD      10.00 ns
   Min tWR         15.00 ns
   Min tRAS      27.00 ns
   Min tRC         50.63 ns
   Min tRFC      160.00 ns
   Min tRTP      7.50 ns
   Min tRRD      7.50 ns
   Command Rate      2T
XMP timings table      CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
   XMP #1         6.0-7-6-18-34-2T @ 666 MHz (1.650 Volts)
   XMP #2         9.0-10-9-27-51-2T @ 1000 MHz (1.650 Volts)

Crucial Ballistix Tactical DDR3 16GB 1866MHz (2x8GB) BLT2CP8G3D1869DT1TX0CEU
   SMBus address      0x51
   Memory type      DDR3
   Module format      UDIMM
   Manufacturer (ID)   Crucial Technology (7F7F7F7F7F9B00000000)
   Size         8192 MBytes
   Max bandwidth      PC3-10700 (667 MHz)
   Part number      BLT8G3D1869DT1TX0.
   Number of banks      8
   Nominal Voltage      1.50 Volts
   EPP         no
   XMP         yes
   XMP revision      1.3
   AMP         no
JEDEC timings table      CL-tRCD-tRP-tRAS-tRC @ frequency
   JEDEC #1      6.0-6-6-17-23 @ 457 MHz
   JEDEC #2      7.0-7-7-20-27 @ 533 MHz
   JEDEC #3      8.0-8-8-22-30 @ 609 MHz
   JEDEC #4      9.0-9-9-24-33 @ 666 MHz
XMP profile         XMP-1866
   Specification      PC3-14900
   Voltage level      1.500 Volts
   Min Cycle time      1.071 ns (933 MHz)
   Max CL         9.0
   Min tRP         9.43 ns
   Min tRCD      9.43 ns
   Min tWR         15.00 ns
   Min tRAS      28.14 ns
   Min tRC         49.50 ns
   Min tRFC      260.00 ns
   Min tRTP      7.50 ns
   Min tRRD      6.00 ns
   Command Rate      2T
XMP timings table      CL-tRCD-tRP-tRAS-tRC-CR @ frequency (voltage)
   XMP #1         6.0-6-6-18-32-2T @ 636 MHz (1.500 Volts)
   XMP #2         7.0-7-7-21-37-2T @ 742 MHz (1.500 Volts)
   XMP #3         8.0-8-8-24-42-2T @ 848 MHz (1.500 Volts)
   XMP #4         9.0-9-9-27-47-2T @ 933 MHz (1.500 Volts)
   XMP #5         10.0-9-9-27-47-2T @ 933 MHz (1.500 Volts)

[AgentFXA]

....
1066 means the memory runs at 533MHz DDR.
I have no idea why the Mobo chooses such a low frequency, when the memory is set to auto.

as already explained earlier..

Sure the RAM can do more.
But is the same true for the memory controllers in the Phenom II ?

The Phenom2 officially is 1333 (666Mhz) ram speed but can do 1600 (oced) - just pull out the Corsairs and see what's up? Okay, but maybe the 100+Mhz speed loss is fine for you to have 24GB!?

Whatever, your call!

[ZdendaV]

OK, I'll give it a shot ...