Asus M5A97 LE R2.0 won't run memory as dual channel, etc

[BasherB]

Updating a current PC with following components and memory not being recognized in part and not running as dual channel:

ASUS M5A97 LE R2.0 970 Socket AM3+ 8 Channel Audio ATX Motherboard
Two x Corsair 8GB (2x4GB) DDR3 1600MHz XMS3 Memory Kit - CL9 (part number CMX8GX3M2B1600C9) - installed as per mobo manual
AMD FX-6300 3.5GHz Socket AM3+ 14MB Cache

Running Win 7 pro 64bit - this reports 16Gb ('but unable to use 8Gb')

BIOS shows only 8Gb - but another part shows each of the four slots filled with 4Gb

CPUID software installed on PC shows each slot filled with 4Gb but only running as single channel

Have used same memory on a different PC with a different model Asus mobo + AMD 8-core processor and that runs all OK and as dual channel.

Any help appreciated

 

[LTC8K6]

IIRC, you can try the ganged / unganged setting in the BIOS.

Dual channel gives no discernible advantage anyway.

Don't worry about it.

 

[VirtualLarry]

Sounds like one of the memory channels on the CPU has failed.

 

[i7Baby]

Try one stick at a time in one slot at a time.

Run Memtest on the sticks.

 

[BasherB]

OK - have taken on board what has been suggested from various quarters and have also dug a bit deeper myself with the components in an attempt to eliminate anything that may show an issue:
Ensured BIOS set for 1600MHz for the memory
Have run MemTest - that reported no problems (with the two sticks that I think may be a problem, but there again may be OK - see further below)
The memory was purchased as two sets of 2 x 4 GB (kits - CMX8GX3M2B1600C9) - 9-9-9-24 CL9
With all four slots occupied: BIOS still reports 16Gb; NorthBridge reports each slot with 4Gb; Windows reports "16Gb (unable to use 7.90Gb)" - have never seen this before on any other PC I've built; CPUID software installed on PC reports each slot occupied with 4Gb - but only as single channel.
Then tried each set separately (blue slots and as per MB manual) - first set showed as above but with 8Gb via BIOS and Windows "8Gb (unable to use 3.90Gb)".
Second set showed similarly as above but only 4Gb via BIOS whilst NB showed each slot with 4Gb as did CPUID software - I then swapped the two modules of this set around and the BIOS and CPUID showed exactly the same: only 4Gb, etc.
This makes me think that the second blue slot may have an issue, which if slots one and two are filled could have a knock-on effect on 3 and 4.
So back to the vendor to get sorted I think!

 

[i7Baby]

The 2 sets of ram might be the problem.

See http://www.tomshardware.com/reviews/ddr-dram-myths,4155.html#p6

"Even though you are buying two of the exact same sets, there is no guarantee that they will work together."