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hagge
Journeyman III

Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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Does the FX 8350 supports two DDR3-1866 in dual channel? And what about four sticks?

I have 2x4GB @1600MHz and want to upgrade it (2x8GB or 4x8GB) but it's not clear in the docs about the limitations of the Memory Controller.

Do I Need to overclock something, just the XMP do the trick or don't support at all?

Thanks in advance.

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techguy
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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The link below shows AMD's official position on FX and other model processors in regards to DRAM capacity and frequency. Your mobo maker also has to support or exceed the capability AMD has built into it's CPU memory controller. DRAM supported frequency varies with the number of DRAM slots on the mobo and how many slots are populated. 1866 MHz. is the highest official supported frequency for the FX CPUs. The later FX-9000 series CPUs support up to 2400 Mhz. DRAM I believe. When populating all four DRAM slots then single or dual ranked DRAM also limits the supported frequency. In my experience and that of many AMD users, with only two slots populated, (2x 4 GHz. DDR3), 2133 MHz. frequency from properly rated 2133 MHz DRAM, functions without issue. You may need to manually set the DRAM voltage and timings if the DRAM (or mobo) does not support AMD's "AMP" or Intel's "XMP" DRAM "auto" overclocking DRAM modes.

It's worth noting however their are minimal gains for CPUs vs. APUs with DDR3 exceeding 1600 MHz. Testing of CPU powered desktops using real applications shows that 1600 MHz. DDR3 DRAM is NOT a system bottleneck. DRAM benchmarks show the potential for higher frequency DRAM not the actual performance experienced with real applications because the DRAM is never saturated 100% of the time in a PC like the DRAM benches use when testing for "potential" performance gain. The GPU section of an APU can benefit from DRAM up to ~2133 GHz. Higher DDR3 frequency DRAM does not produce any tangible system performance gains using real apps.

DDR3 memory frequency guide

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qbtheslayer
Challenger

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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I'm not sure about 4x8GB...  but I am running 4x2GB right now with no issues.  Although with my revision 1.0 motherboard (released just before the FX line was released) I do need to bump up my CPU-NB voltage (the voltage for the IMC) a wee bit.

QB

brucer
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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you should be running 2133mhz memory for best performance.. usually I'll get memory that is higher clocked than specified for the motherboard... 

your mobo is capable of running 2133mhz memory, so I would get 2400mhz memory if I were building it, the motherboard would run it up to 2133mhz.. Which in my experience memory lasts far longer doing it like this..

copy and pasted this from your mobo spec page.

  • DDR3 Memory   

    DDR3 800/1066/1333/1600/1800*/2133*(OC) 

  • Memory Channel   

    Dual 

  • DIMM Slots   

  • Max Memory (GB)   

    32 

techguy
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

Jump to solution

The link below shows AMD's official position on FX and other model processors in regards to DRAM capacity and frequency. Your mobo maker also has to support or exceed the capability AMD has built into it's CPU memory controller. DRAM supported frequency varies with the number of DRAM slots on the mobo and how many slots are populated. 1866 MHz. is the highest official supported frequency for the FX CPUs. The later FX-9000 series CPUs support up to 2400 Mhz. DRAM I believe. When populating all four DRAM slots then single or dual ranked DRAM also limits the supported frequency. In my experience and that of many AMD users, with only two slots populated, (2x 4 GHz. DDR3), 2133 MHz. frequency from properly rated 2133 MHz DRAM, functions without issue. You may need to manually set the DRAM voltage and timings if the DRAM (or mobo) does not support AMD's "AMP" or Intel's "XMP" DRAM "auto" overclocking DRAM modes.

It's worth noting however their are minimal gains for CPUs vs. APUs with DDR3 exceeding 1600 MHz. Testing of CPU powered desktops using real applications shows that 1600 MHz. DDR3 DRAM is NOT a system bottleneck. DRAM benchmarks show the potential for higher frequency DRAM not the actual performance experienced with real applications because the DRAM is never saturated 100% of the time in a PC like the DRAM benches use when testing for "potential" performance gain. The GPU section of an APU can benefit from DRAM up to ~2133 GHz. Higher DDR3 frequency DRAM does not produce any tangible system performance gains using real apps.

DDR3 memory frequency guide

View solution in original post

qbtheslayer
Challenger

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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brucer wrote:

you should be running 2133mhz memory for best performance.. usually I'll get memory that is higher clocked than specified for the motherboard...

your mobo is capable of running 2133mhz memory, so I would get 2400mhz memory if I were building it, the motherboard would run it up to 2133mhz.. Which in my experience memory lasts far longer doing it like this..

copy and pasted this from your mobo spec page.

  • DDR3 Memory

    DDR3 800/1066/1333/1600/1800*/2133*(OC)

  • Memory Channel

    Dual

  • DIMM Slots

    4

  • Max Memory (GB)

    32

Well this is not a very useful post, since it requires an OC on an FX-8350 to get above 1866.  You then need to know how to push the FSB past 200 and how to adjust all the other ratios that are based on the FSB.  I'm sure this is not what the OP was looking for.

QB

brucer
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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How does it require a cpu overclock?

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techguy
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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My intent is NOT to be offensive but what you have stated is complete incorrect. You might want to review my comment for a better understanding of DRAM frequency vs. system performance. I am aware that there is a lot of mis-information on DRAM frequency/performance as the DRAM sellers want people to buy the more expensive higher frequency DRAM that does NOT deliver any tangible improvement is system performance, as has been illustrated in test with real applications.

FYI - All DDR3 DRAM starts out as 1333 MHz. and is speed binned to whatever the max frequency it can run at reliably. The DRAM suppliers just charge more for the DRAM that can operate stable at a higher frequency, just like with CPUs.

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brucer
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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really? so I guess ddr3-800 and ddr3 1033 start out at 1333? lol

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techguy
Forerunner

Re: Does the FX 8350 supports two or even four DDR3 @1866MHz in dual channel? The mobo is a MSI 990FXA-GD80.

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DDR3 industry specs are for 1333 MHz. Deviations from the base frequency are by choice.

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