2x8 Corsair Vengeance 2666MHZ wont work

[defjused]

Hello!

I have just bought 2x8 Corsair Vengeance DDR4 2666MHZ Ram sticks but for some reason they
only work when i lower the ram speed to 1066, anything higher than that wont let me boot into BIOS or windows. If i only use one stick then i am able to use higher ram speeds.

Motherboard: ASUS PRIME Z370-A

Anyone know how to fix this? Appreciate all the help!

 

[TJ Hooker]

Are you manually selecting the frequency? All you should have to do is enable the XMP profile (leaving everything else on auto/default).

 

[defjused]

Yeah now i've had to manually select the frequency to 1066mhz otherwise BIOS / Windows wont bot, but in the beginning everything was default and thats when the 2 sticks didn't work together unless i lower the speed to 1066mhz. When i insert one stick the speed goes up to 2133mhz. Getting very annoyed

XMP doesn't work with 2 sticks, ive tried enabling it with one stick and then restarted the computer and put in the 2nd one but wont work.

Edit: Maybe i have to increase the voltage or something?

 

[TJ Hooker]

What's the exact model of RAM?

 

[defjused]

Corsair 16GB (2x8GB) DDR4 2666Mhz CL16 Vengeance LPX

https://www.corsair.com/uk/en/Categories/Products/Memory/VENGEANCE%C2%AE-LPX-16GB-%282x8GB%29-DDR4-DRAM-2666MHz-C16-Memory-Kit---Black/p/CMK16GX4M2A2666C16

 

[Kasper Jorgensen]

1066 MHz is Double Data Rate (DDR) meaning it is effectively running 2133 MHz.
As said above, just load the XMP profile to get the higher speed. 2666MHz will sometime in some software be displayed as 1333MHz.

 

[defjused]

1066 MHz is Double Data Rate (DDR) meaning it is effectively running 2133 MHz.
As said above, just load the XMP profile to get the higher speed. 2666MHz will sometime in some software be displayed as 1333MHz.

Oh, so each one of these sticks is actually running at 2133 MHZ but it just says 1066MHZ?

The thing about XMP is when i enable it the pc wont load into bios or windows, but with one ram stick it works perfectly.

 

[TJ Hooker]

Yes, the effective transfer rate that is advertised for RAM (i.e. 2666 MHz) is double the actual memory clock (1333 MHz). Some utilities report the effective transfer rate, some report the memory clock.

That's quite surprising it wouldn't be stable at 2666 MHz. That isn't a super high speed so I would expect it to work fine on just about any intel system, plus that kit is on the QVL list for that mobo.

What memory slots are they installed in? They should be in the 2nd and 4th slots (counting upwards as you go further away from the CPU socket). If that still doesn't work, can you confirm that you can run a single stick at 2666 MHz in both of those slots? You can also try increasing the memory voltage a bit after enabling the XMP profile.

Ultimately it should work just fine, and you may have to contact Corsair and/or Asus about the possibility that you have a shoddy motherboard or memory.

 

[defjused]

They are installed in the 2nd and 4th slot (the gray slots) although i've tried them all. I tried out all the slots and it turns out the sticks only get 2666MHZ in the left slots ( one black and one gray). It says it runs at 2666MHZ in the BIOS information but then when i look at the DRAM status information it says 2133MHZ. In the right slots grey&black they run at 2133MHZ.

I managed to get into BIOS with both sticks together after pressing ''MemOK'' 50 times on the motherboard but then when i exited BIOS the same issue occurre dagain..

When i enable XMP it says the ram sticks are running at 16-18-18-35-1.20V. How much should i increase the voltage?

EDIT: Now im back at 1066MHZ with both sticks working.

Thank you for trying to help me, really appreciate it!

 

[TJ Hooker]

Hmm, not sure, maybe try 1.3 V.

Forgot to say, make sure your BIOS is up to date if you haven't already.

 

[defjused]

Alright will try. BIOS is up to date.

 

[defjused]

Did not work, will return the motherboard and the ram sticks so they can check what the problem is.

Thank you for the help, much appreciated.