990FXA-UD3 Dual-Channel Memory Probem

[7054]

Hey all,

Names Josh.  I have run into a problem and have scoured the web in search of a solution to no avail.

I have a Gigabyte board (990FXA-UD3 rev1.1) with a FX-8150 and 32GB (8x4) of G.Skill Ripjaws Dual Channel memory.  For some reason both Windows and CPUz both show my memory as Single channel.  I don't think there is a performance loss due to this but it has been bothering me that I'm seemingly not operating at optimal performance. 

Anyone have any idea's as to why this may be?  Thanks.

Also, my apologies if I've managed to miss a often overlooked solution.  I promise I have thoroughly researched this.  I've attached a text document with my system specifics as shown via Piraform Speccy

[autotech]

I had this problem in the past what caused it was cpuz had not been updated recently so it couldnt read my specs just right at that point it had my ram and my video card wrong. When it was updated that fixed it. The only other time it showed it as single channel i think i changed it in bios to unganged and set all memory timings manually and that took care of it.

Other than the above i havent run into it hope this helps some. 1.62 is latest version of cpuz and i am not sure of the date of release for it.

[7054]

Thanks for the reply but I checked and CPUz is the most current available.  It's not only CPUz that is reading it this way.  Several benchmarking apps display it as such as well. 

Memory is mostly set to Auto at the BIOS, though I have manually changed settings in hopes to resolve this and not seen any change. 

Hmmm.  No idea why it's doing this. 

[k-9]

sorry if this is late. do you have the memory in the same color slots.

[7054]

I have 4 slots on the board all filled by 8GB G.Skill F3-14900CL10-8GBXL sticks which should give me 32GB's but I only have 16GB.  Right now Windows says I have 24GB's installed and 16GB usable.  At post it shows 16GB.

[absic]

Hi there,

what BIOS version are you running?

[7054]

F9

[Ripshod]

Don't know if it's relevant - taken from the Corsair forums:

It is a long standing problem with AMD CPU's and it has happened ever since the single core amd 64's were released. and the issue is .
that the memory controller can not run at max speed with fully populated ram.
in the old single core days, they couldn't even run in dual channel! they would revert to single channel as the control would not handle the load. so in that sense it has improved a little. true story I made AMD send me a revised chip when the AMD 4000+ was the best CPU out, it cost me a fortune I think it was almost 1000 dollars back then.
and so I did the same thing bought the best ram, and the same thing happened, so I called AMD and spoke to their engineer, who was aware of the problem, but I explained it was false advertisment as the box said dual channel ddr 400. so he sent me a engineering sample of the revised stepping of the 4000 and let me keep the old chip !!, that was a good day for me .... haha

There is a few reasons I don't want you to worry about this. and I understand you are going to be frustrated after what I have said, so here goes.
I know you bought 1600C9 sticks so you could have fast memory, so I get that
but what you also need to know is AMD's memory scaling doesn't respond too well to Raw speed anyway. meaning the AMD on Die memory controller runs at 1333 mhz. So running it any faster is pretty much useless. sure you may get a little speed. but you are essentially making a bottleneck.
However What AMD CPU'S respond really well to, is matching their memory controller speed. So 1333 mhz, and getting the tightest timings possible.

[7054]

I'm running at 1333mhz.  Thats what the board defaults to if left untouched.  I've tried other speeds and various other settings though. 

I've tried them individually, at which point they read as 8GB at post, but as soon as I go beyond one stick, regardless of slots occupied it becomes halved.  So 2 sticks yields 8GB, 4 sticks yields 16GB. 

I'm thinking that this memory just isn't fully compatible with this board.  I dunno what else to think.  Can't wait to spend another $250.00 or more for another 32GB.   

[klh591]

Your problem could be 1 of 3 possibilities.

1.  one or more of your memory sticks are bad.  Use a memory checking program to verify your sticks.

2.  one  or more of your motherboard memory slots are bad (Very unlikely).

3.  in your BIOS on the memory page ganged/unganged should be set unganged (most of the time).

I am currently down to 5 Gigabyte 990FXA boards (3 - UD3,  2 - UD5)  all with 4 sticks (4 - 4X4,  1 - 4X8) of 1600 speed memory or
above and they ALL show"dual channel".

[7054]

I've run MemTest several times and the were no errors and nothing that suggested anything was wrong with the memory other than during the test it showed 16GB not 32GB. 

I've tried every combination of 2 possible thinking that 1 was bad but all the combination produced the same result.  Would show 8GB of memory in single channel. 

Memory is set to unganged, though I have tried ganged thinking that just maybe that would help. 

The board is 1.1, purchased from Newegg as Refurb I believe, or clearance, can't remember.  The memory was all brand new from Newegg.  Starting to wonder if maybe it's the board.  Maybe not the slots themselves but something else that would prevent the memory from working as designed. 

[7054]

Running MemTest on individual sticks of memory in each slot I found that slots 2 and 4 will not post when memory is only in that slot.  Thinking bad board?

[heystek]

Did you ever solve this issue? I am running into the exact same problem and I can't figure it out. Thanks!

[7054]

No not really.  I basically figured it was the board.  Board was a refurb and Newegg wouldn't do s**t to help me due to the length of time.  Pretty much I was screwed.  Solved it by joining the dark side and buying a Mac.  Haven't looked back. 

Wish I could be of more help. 

[heystek]

Thanks for the quick reply. We already tried to RMA the motherboard and it didn't make a difference.