Dual channel mode not working

Hi all,

I'm having a HW issue with my recently upgraded PC: my motherboard fails to
work in dual channel mode, i.e. when I mount RAM on slots 3 and 4 (as
indicated in the manual), I get a black screen (vents go on, but no beep or

Only if I mount RAM on slots 1 and 3, I can get further, reach BIOS, and

I've got this failure after some kernel panics... my system was running
fine with 12GB of RAM, two modules are Kingston KVR1333D3N9 (2 x 4GB) and
two are OCZ Reaper PC3 10666 (2 x 2GB). I've upgraded this RAM config a
couple of years ago and only now I'm recognizing the dimms are of different
voltage (1.5v Kingston, 1.75v OCZ). In the meantime I also found one OCZ
dimm is broken.

I've removed the OCZ and the system now runs with the Kingston memories
only on slot 1 and 3 (8 GB).

BIOS is updated to the latest version. I also changed the CMOS battery
against a fresh one. The board is an ECS A790GXM-AD3 (see
and runs an AMD Phenom IIx6 1100T cpu.

1) Is dual channel "broken"? Can I do something about it?
2) Whatever the answer to 1) is, can I mount these Kingston DIMMS
(KVR1333D3N9K2/8G, see spec here
http://www.kingston.com/dataSheets/KVR1333D3N9K2_8G.pdf) on slots 1 and 3,
so that I get 16GB of RAM?

Any help'd be greatly appreciated, thanks!

attachment.htm (1.69 KB)

Hi Pasquale.

Got a look to the m/b manual (page 16).
You may try different position for your Kingston KVR1333D3N9 (2 x 4GB), just to test if system is starting; according to the manual any of the following should start.
Detach all devices from system (no disks!), leave just monitor + keyboard; after every start goto BIOS to inspect memory configuration discovered by the system.

DIMM 1 & 2: using 8GB as channel 0 (no dual channel mode)
DIMM 3 & 4: using 8GB as channel 1 (no dual channel mode)
DIMM 1 & 3: using 8GB in dual channel mode
DIMM 2 & 4: using 8GB in dual channel mode

If the system starts with all of the 4 configurations, you should have tested that
- the 4 DIMM's sockets are all working
- the dual channel mode is working properly


Hi Pasquale,
I see that the description and figures in the manual are a bit confusing.

According to page 16
Channel 0: DIMM1, DIMM2 (should be both orange)
Channel 1: DIMM3, DIMM4 (should be both yellow)

According to table on pag. 17
Channel 0: DIMM1, DIMM3 (should be both orange)
Channel 1: DIMM2, DIMM4 (should be both yellow)

The before suggestion are still valid, but BISO should tell you what is the discovered configuration.


Yes, you're right: the picture on pag 17 shows a different dual channel
config as found on the mainboard.
Mine looks like this

Slot 1+2 are orange, slot 3+4 are yellow.

According the table on page 17, 4 RAM modules should be inserted first in
slot 3, then 4, then 1, and then 2.

So, ok, I'm lost :slight_smile:

attachment.htm (5.25 KB)

No, you are not.
Give a try to
DIMM 1 & 2:
DIMM 3 & 4:
DIMM 1 & 3:
DIMM 2 & 4:
and let us know.


attachment.htm (6.32 KB)