two sticks of 1333 MHz memory yields speed of 1066 ?

[Mark]

I'm the one who asked about using multiple sticks of memory and how it would cause the memory speed to be reduced.

I've got several axes to grind about this one, but today's mystery is:

If I install two sticks of 1333 MHz memory, why does the system run it at 1066 MHz?

I would understand (not really, but I'm told so) if I had FOUR sticks of memory the system would run the whole thing at 1066.

And, in fact, I started with 4 sticks of memory.  It worked fine (at 1066) until I did a 24-hour burn-in and had to pull two memory sticks.

Now I'm down to two 2-gb sticks, and the system continues to insist on running the memory at 1066 instead of 1333.

Is this expected?  Should I clear CMOS and hope the system recovers?

Mark

[oggmonster]

Yeah you could try clearing the CMOS and see if it auto detects the settings. Or you may have to manually set RAM speeds + timings. My 1066mhz ram was automatically configured to run at 800mhz untill i changed; timings, fsb ratio (you're using p55 so you wont have a fsb ratio as such ) and volts

[jamostew]

I'm having the same problem, but with 1600 showing as 1333.

I read a comment by a webstore buyer that they resolved this problem (incorrect memory speed at post) by updating their bios to the latest BETA version.  Tread carefully if you decide to venture down that path!

[Mark]

I updated yesterday to BIOS F5d and ran prime95 all night long with no problems.

I haven't tested anything other than prime95, but it looks like the CPU / memory aspects are working correctly.

[oggmonster]

I updated yesterday to BIOS F5d and ran prime95 all night long with no problems.

I haven't tested anything other than prime95, but it looks like the CPU / memory aspects are working correctly.

I thought you had latest BIOS  But nice, looks like you're getting there 

[Mark]

I'm sorry, but I don't understand your comment.

To be perfectly honest, I don't know what version of BIOS I had prior to updating to F5d yesterday.

Yesterday I updated to F5d, which I think is the very latest BIOS.

I did backup the BIOS before I updated, so I could go back to it and find out.

[oggmonster]

From our previous convos I thought you already had the very latest BIOS revision that was all.

[Badbonji]

The motherboard usually has default settings for memory, and will use it no matter what speed your memory is. Your memory has multiple profiles for timings and speed, and the 1333Mhz is the highest speed profile. Some motherboards have an option for "XMP" or Extreme memory profile or what not, depending on model. So check for an option, otherwise do it manually.

There is nothing bad about doing it manually, just make sure to check the timings and voltage settings. Is this a 775 system or a AM2+???
4 sticks vs 2 create more stress on the memory controller, so you may need to up the voltage a bit on the NB as it is usually down to the motherboard rather than the memory why it is unstable.

[Mark]

I think I need to better understand what settings are default, what settings are read from the memory.

I just changed the multiplier from AUTO (x8) to x10 and I'm running Memtest86+ v2.11.  It's 20% through the first pass, no errors yet.

The memory (Patriot Viper II Sector 5) runs 7-7-7-20 normally, and has an XMP profile of 6-6-6-17.  I tried XMP once and it didn't work, but maybe that's because the memory voltage is 1.5, and Patriot specifies 1.6?