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Ddr3 1866 posts at 1333

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October 21, 2011 11:11:59 AM

Hello,
At post, my memory is listed at 1333 when it is actually 1866. (My mobo 990-fxa supports 1866 without OC) Do I correct this in the bios? If so, how? Any replies are appreciated. Thank you

More about : ddr3 1866 posts 1333

a b } Memory
October 21, 2011 12:02:14 PM

Is the make and model of your RAM listed in the QVL of the Board?
Is it placed in the correct slots as mentioned in the manual?
And let's hope you are not mixing and matching RAMS of different timings on a single board.
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October 21, 2011 12:19:06 PM

ok, go in your bios and choose the respective profile...that's what i had to do with my 1600 mhz....at first it was posting at 1066 mhz
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October 21, 2011 12:30:24 PM

I`ve gone into bios and changed it to 1866. Then I received a warning that system wouldn`t boot properly. The ram I installed is listed on the gigabyte website as compatable. 990-fxa 16 GB ddr3 1866. Limit of board is 32 GB. Thanks for your reply
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a b } Memory
October 21, 2011 12:32:27 PM

Is that a single slot 16GB DDR3?
What processor are you using?
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October 21, 2011 12:39:23 PM

alyoshka said:
Is the make and model of your RAM listed in the QVL of the Board?
Is it placed in the correct slots as mentioned in the manual?
And let's hope you are not mixing and matching RAMS of different timings on a single board.

Hi, thanks for the reply. All 4 modules are identical and use all 4 slots. 16gb. (Board will take 32gb) The ram is listed on gigabyte`s website as compatible. I went into bios and changed it from 1333 to 1866 and received a warning that system will not be able to boot. Any other thoughts? Thanks again
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a b } Memory
October 21, 2011 12:40:27 PM

Guess what I found out??????

"You will need to set your CPU clock (or known as FSB) to 233MHz to achieve 1866.
But keep in mind that this will also increase your CPU, CPU/NB, and HT Link frequencies as well.
Since your 1100T is a Black Edirion, adjust your CPU multiplier to the desired CPU speed/frequency.
Then, you will need to set the CPU/NB frequency in the 2800MHz range to match your 1866 memory speed.
The HT Link does not (or need) to be overclocked, keep it in the 2000-2200 range.

Don't forget to manually enter you memory timings and voltage in your bios. "

http://www.tomshardware.com/forum/293252-30-skill-snipe...

Of course , yours may not be a 1100T but the point is you will need to change the FSB multiplier to be able to achieve the 1866 timings required.
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a b } Memory
October 21, 2011 2:30:41 PM

DDR3 1866 is supported via a memory divider when you install a FX based processor.
The IMC (Integrated Memory Controller) of a Zambezi has a native support of DDR3 1866. So when you're trying to run your RAM @ 1866 you need to basically overclock it. And it's not recommend to OC your RAM @ 1866 because the IMC of a Phenom II is capable of 1333 MHz.
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a b } Memory
October 21, 2011 4:06:05 PM

Correct Phenom II CPUs have a default RAM frequency of 1333 MHz. Zambezi has a default RAM frequency of 1866 MHz. Many Phenom II CPUs will NOT run RAM @ 1866 MHz. so you might be stuck with 1333 MHz or perhaps 1600 MHz.

In addition most mobos will revert to the default CPU/RAM frequency when all RAM slots are filled so with Phenom II this would be 1333 MHz.

FWIW, there is typically ~1% system gain from bumping the RAM frequency a few hundred Hz. so it's not worth the effort unless your PC is 100% stable with OC'd RAM.
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October 21, 2011 9:12:09 PM

alyoshka said:
Is that a single slot 16GB DDR3?
What processor are you using?

I`m using the FX-8150. 4X4 gigs 1866. Gigabyte 990 fxa-ud3 .
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a b } Memory
October 22, 2011 8:15:10 AM

From my understanding, when the FX is working at it's default speed ie. 3.6GHz your RAM is going to be functioning at 1333MHz and when under load the turbo cores will kick into play boosting the CPU clock speed to 4.2GHz and the RAM speed to 1866MHz.

I must say, I am not a 100% sure about this, since I still haven't managed to get my hands on the FX8150, yet, but by logic this ought to be the way they multiply.

I can suggest to you one way to test this and see, stress the CPU with a CPU stresser like the Intel BrunIn test and have the CPUz program running side by side.
Get a screenshot and lets see what it's like.
I'd like to see it.
The board supports 1866MHz RAM, the Processor supports a native 1866MHz DDR3 so I really can't see why it shouldn't be running at those speeds.
But this test would put some light on the issue.
I would also like you to reset the BIOS to defaults before you perform these tests.

Edit:
Goin through your BIOS right now, there is an option that says Set Memory Clock Under DRAM Configuration. It is set to x6.66, you can change that to x8.00 , save and reboot and check too. Check Page 36 and 37 for more information in the Mobo User Manual.
Also make sure you have the latest BIOS released, it's F5 I think.

http://www.gigabyte.com/products/product-page.aspx?pid=...
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October 22, 2011 2:48:34 PM

Best answer selected by jamesr10962.
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