Why is memory running at 1333 on GA-990FXA-UD5

[sdunnin]

I have a GA-990FXA-UD5 with a FX-8150 cpu installed and 1866 DDR3 RAM. Yet, it is running the RAM at 1333. I thought the 990 chipset and FX cpus are supposed to run 1866 out of the box? Do I have to OC the mem to get it to run at 1866? I didn't think that I would have to do that with the FX.

System Specs:
GA-990FXA-UD5
AMD FX-8150
ARCTIC COOLING Freezer 7 Pro Rev.2 CPU Cooler
G.SKILL Sniper Series 16GB (4 x 4GB) 240-Pin DDR3 SDRAM 1866 (PC3 14900) Desktop Memory Model F3-14900CL9D-8GBSR
2 x OCZ Vertex SSD with 1.7 firmware
1 WD Caviar Green 640 GB HDD
1 Seagate 250 GB HDD
EVGA GeForce GTS 250 1GB

[Dark Mantis]

Hi

As the highest JEDEC standard is 1333 anything over that is an overclock.

[sdunnin]

Guess that I was a little bit mislead by the specs then http://www.gigabyte.us/products/product-page.aspx?pid=3891#sp


Support for DDR3 2000(O.C.)/1866/1600/1333/1066 MHz memory modules (Note 2)
...
(Note 2) To support a DDR3 1866 MHz (and above) memory, you must install an AMD AM3+ CPU first.


The way that reads to me is that only to go above 1866 do you need to OC.

[Dark Mantis]

No, you don't need to overclock the entire system only the memory. The previous chips would burn out the memory controller if you tried to run the memory at over 1333 but these new CPUs will be ok.

[sdunnin]

Guess I'm still a little confused over the need to OC the memory but I will give that a try. Is the EasyTune utility the best method for that?

[absic]

No, you're better off setting the correct timings in BIOS under the MIT Section. You should just need to increase the Memory Clock to X9.? but you may also need to increase the RAM voltage depending on the spec's of the RAM you are using.

Just to clarify the issue of RAM speed for you.

The FX processors will run RAM modules rated above the 1333MHz speed and up to 1866MHz quite safely. If your RAM is rated above 1333MHz you are not really overclocking it but the system BIOS sees it as this as a safety precaution (because of the backwards compatibility with the AM3 processors) and because, as DM has said, because of the JDEC Specifications. This is why you have to manually set the RAM Speed and also possibly the voltages and timings to those specified for your modules.

[sdunnin]

Is that a trial and error type thing with the mem voltage or is there some sort of OC spec guideline that you know of?

[absic]

What RAM modules are you using? EDIT: OK if I read your original post I would know that..... Doh!  

on the packet it should tell you the Voltage as well as the timings for them. These are what you need to set in BIOS.

RAM will be set at the default voltage of 1.5V. If, for example, your RAM is rated to run at 1866MHz at 1.65V then you will need to set the RAM voltage to that. With your modules you shouldn't need to do this. When you go into the voltage control section of BIOS it is pretty straight forward and it will show you the available voltage settings. When you move above 1.5V you will get a red warning message flashing on the right-hand panel about over volting the system but this can be safely ignored.

Just a thought but, as you are running a 4 stick kit, you may find that the system will not BOOT properly (this has happened on the GA-990FXA-UD3) when you increase the RAM speed to 1866MHz and it only BOOTS with 2 sticks of RAM. We haven't got to the reason for this yet and it may not happen on this motherboard, but forewarned is forearmed as they say.

[xLyallx]

I also  have a GA-990FXA-UD5 with a FX-8150 cpu installed and 1866 DDR3 RAM.Got mine running the RAM at 1600 with all4 sticks of ram or 1866 with only 2 slots populated.Is this a hardware issue or software,is there a fix perhaps a bios update(my friend has another make of motherboard with my cpu and ram all ram slots populated running at 1866) .I have been in touch with gigabyte technical support and got this response:-
Hi,

Gigabyte bios read the memory SPD value, according to the CMZ8GX3M2A1866C9 specification the SPD programmed at JEDEC standard 1333MHz. You can try to manually adjust the memory timing and we not guarantee the performance.
 

[xLyallx]

Hi I've done allot of reading and seems that the  amd fx memory controller cant run two channels at 1866
read this http://forum.giga-byte.co.uk/index.php/topic,7345.0.html
and some people have managed to get there ram running at 1866 by manual settings and over clocking I've had no luck yet but I will keep trying

[sdunnin]

xLyallx,
You are correct in your research about the FX and dual channel problems @1866. There is a long topic in this forum about this very subject http://forum.giga-byte.co.uk/index.php/topic,7345.0.html. It hasn't had a post in a month or so but does contain alot of information from various members' experiences with trying to get the memory to run @1866.

Personally, I OC'd mine to 1600 and have left it there as it seems to be working fine and I would rather use the whole 16GB @1600 rather than run 8GB just to go from 1600 to 1866. I tried to get 1866 a couple of times but abandoned it as I just didn't have the time for so much experimentation.

[xLyallx]

Yeah I'm at 1600 with 16Gb just wish AMD was a bit clearer with there info (This processor half supports 1866) What gets me is some people have got the same ram,  processor &  motherboard to run at 1866 using manual settings or even profile 1 and I've had no joy