RAM compatiblity issues - 8 DIMMS running at different speeds

henry667

Reputable
May 16, 2015
2
0
4,510
Hey guys,

I am a bit confused, I have a Sabertooth X79 motherboard which has 32GB of Corsair Vengeance RAM installed. I recently ordered a further 32GB of RAM also Corsair Vengeance.

Here are 2 pics of the Ram Types installed:
image.jpg

image.jpg


You can see the small difference in the serial number, but thats to be expected as they are more "modern" versions after the now 3 year old Corsair Vengeance modules I have.

They were advertised as being the same speed and of the same model so I thought it would work.

I try to use the XMP Profile in the Bios, and whenever I turn the computer off and on again, it fails to boot at first, the restarts (American Megatrend) telling me Overclocking failed.
I go into the Bios and simply select (Discard Changes) and reboot, it then boots as normal.

Does that mean it disables the XMP mode and uses the memory at "safe" but slower settings to work?

I thought Ram slightly faster (the newer ram) would just reduce down to the level of the slower ones and run at that level without anyproblems.

There are no issues in using the computer at all once it is used. That includes rendering/gaming for hours.


Do I have to manually setup the 2 different sets of 4 RAM modules so that they work together at their maximum speed?

When I go into the BIOS, I see that the 2 differents sets of RAM run at diferent speeds, effectively 1333 and 1600mhz. How is that even possible?


Btw Motherboard drivers are the latest.

Thanks for any help :)

 

Tradesman1

Legenda in Aeternum
The newer ones will have a default boot of 1600 which is probably what you are seeing (the older have a default of 1333) check CPU-Z in the memory tab too find what all are actually running at (they will all be running at the same either 1333 or 1600). If CPU-Z shows 1333 (which will appear as about 667, since this is DOUBLE data rate, then set manually to 1600 and spec timings
 

henry667

Reputable
May 16, 2015
2
0
4,510
Wouldn't setting it to XMP Profile do just that? I assume it sets it slightly differently for the 2 sets which causes the problem?
So do you mean I should copy the timings from one to the other (tRAS,tRC,CAS, any others?)