990FXA-UD5 v1.0 All RAM not shown

[Unclebark]

The problem I am having is not all of my RAM is being recognized.  POST shows 16Gb, & Windows shows 20Gb with 16 usable.  CPU-Z shows 32Gb and when I benchmark with 3dMark it displays 32 as well.

My system is :

Gigabyte GA-990FXA-UD5 v1.0 (F12 bios)
AMD Bulldozer X8 FX-8120 8-core 3.1GHz AM3+
2 x Gigabyte HD6870 915MHz 1GB-DDR5256BIT PCI-e (crossfire)
2 x G-SKILL Ripjaws X Series 16GB (2x8GB) DDR3 1600MHz CL10 Dual Channel (F3-12800CL10D-16GBXL) (32GB total)
Corsair HX850
240GB SSD (Windows drive) Windows 8.1
3.5TB HDD (1x2TB, 1x1TB, 1x500GB)
1x Blu-Ray R/W Optical Drive
Pavilion 23tm Touch monitor

I have posted on the RAM's forum and tried the settings that were presented to me with no luck.  I am able to OC the RAM and CPU, but not get all 32Gb of RAM.  I did buy 2 sets of the same RAM, so it was not a 32Gb set.

I am asking if anyone knows that it is a motherboard issue or an issue of the RAM being 2 different packages.

After wandering around this forum I am thinking it might be both and I may just have to live with 16 until I can get a single 32 set, or is there a board that will use both?

Thanks for looking!

[absic]

You say you are running the latest F12 BIOS but have you tried an earlier version to see if that makes a difference?

Your processor is supported from the F5 BIOS so I would try BIOS versions from this one, as sometimes things get altered as newer revisions add updated processor info etc.

Remember to load Optimized Defaults before you re-flash the BIOS, especially as you have been O/C'ing and use the QFlash utility for BIOS flashing.

[Unclebark]

Hi absic, thanks for the reply.

No, I have not tried that, yet.  I will give it a try over the next few hours and see.

[Unclebark]

Well that went......poorly.  Decided to start with the first release BIOS and it went downhill from there.  Used @BIOS to flash the old BIOS and turned my pc into a brick.  Would power on but would not even POST.....just kept spinning.  After spending a few hours trying to correct this, I conceded defeat.  When your keyboard won't even start, what can you do??? 

The good news is I now have a shiny new 990FXA-UD3 v4.0!  Put it together, and WHAM!! 32Gb of RAM.

Don't think I did anything wrong flashing the BIOS, except going too far back.  Have used the @BIOS  utility before, maybe got a little cocky......usually costs me money when I think I know it all!!!

[Tiger]

Mixing two 16GB kits is not recommended or guaranteed to work. You might try running at a slower memory clock. You should use a single 32GB kit which is guaranteed to be compatible.

From G.Skill FAQs:
 
Q:
 I want to install more memory, in addition to my existing memory kit. What are my options?

A:
 We do not recommend mixing memory kits, regardless of brand or model.

 By mixing memory kits together, there may be compatibility issues such as unable to boot or unable to operate at rated specifications.

 Each of our memory kit are thoroughly tested to ensure compatibility within each memory kit. And because we have not tested our memory kit with your existing memory kit, we cannot guarantee compatibility when multiple kits are used.
 

[Unclebark]

Hello Tiger. Thanks for the reply.

The fact I had 2 separate kits was the problem I was leaning towards.  I had hoped there was a work around or BIOS settings that could change this.  It is unfortunate that I could not continue working on it.
Installed the 2 kits into a newer board and they worked find, so far, from first power on, so it looks like the board does matter.

[absic]

Sorry to see that you bricked your mobo when BIOS flashing but I did recommend using the QFlash utility as this is run through BIOS and not through windows.

Still, you now have a new board and everything is working OK so that is good.

As Tiger has said it is not recommended to mix RAM modules. That said, I have had to do this on many occasions and although it can be a little tricky, getting them to play together nicely, it can be done.

[Unclebark]

Lesson learned, absic.  Like I said, I got cocky because I had always had success with @BIOS.  Won't be making that mistake again.....and because of a "Black Friday" sale, I did get a good price on the new mobo. 

Thanks again for your advice.

[dmdilks]

On the memory as long as they are the same speed and timings and the same brand memory is memory. If you use the same speed and timings but two different brands you could run into some problems.

I must be very lucky because I do it all the time. I did the same thing he did with my Ga-x79-UP4. Two 16gb kits but everything was the same. Ran great for almost 2yrs.

Plus I'll do the same thing on my Ga-x99-UD4 once the memory price comes down a little.

[Unclebark]

So far everything is running smooth. I haven't really pushed it, just some gaming, but the difference is what I had hoped.  32Gb is great!!  Going to start OCing shortly to get my cpu back up around 3.9GHz....never could pass 4 on the old board.....and get the RAM to 1600.

Speaking of the old board, I dug up an old Phenom II, plugged it in and the board started fine.  Now I have something to practice on before I make major changes to my "good" system.

Cheers!! and thanks for every ones input.

[dmdilks]

That CPU will support up 1866 memory. On memory that once you get pass 8gbs how much do you really use.

I think it is more bragging rights than anything. I have a older 2011 i7 and on that board I ran 32gbs of memory.

I have a new 2011 v3 i7 and on that board I have 16gbs of memory. I don't really see any change.

Plus always felt that when you run 1066, 1333, 1600, 1866, 2133 & up. That the normal person will not a speed change.

But glad that you are happy and everything is running OK.

[Unclebark]

Without a doubt it is about bragging rights!!!!    I have been noticing a slight improvement, or at least I am hoping that is it.  It seems a little.....smoother....if that is the right word.  That could be more due to my tweaking than any actual hardware, but still.....32Gb.....am I right??