CMX4GX3M2A1600C9 dual channel kit not running at 1600 mhz on AMD Phenom II x965

[viro2409]

Okay, I have a Asus M4N75TD motherboard, and a Phenom II x965 processor. The motherboard manual claims that this corsair memory should be completely compatible, which is why I selected it.

Unfortunately, the memory defaults to 1333 mhz setting and it won't run stable at 1600 mhz ( not even stable enough to boot Windows) even if I bump the voltage up to 1.65, although the system runs just fine at the 1333 mhz setting, I don't understand what the problem is. :confused: Any help would be appreciated.

[trackrat]

In order to run at the rated speed, i.e. 1600 MHz the RAM voltage must be set to the Corsair specified voltage for your RAM which is typically 1.65V for AMD use DDR3. In addition your CPU/Mobo/RAM/PSU must all play together nicely for you to be able to run the CPU/Memory OC'd @ 1600 MHz. as the AMD socket AM3 CPUs are only guaranteed to run at 1333 MHz. not 1600 MHz. If you are using "auto" settings in your BIOS it will set the RAM frequency to 1333 MHz. as that is the highest that your CPU is rated at.

 

You might want to try adjusting the memory settings in BIOS manually and upping the CPU-NB voltage to 1.20V and reading Dolks Phenom II tuning guide at the link below. Running the RAM at 1600 MHz. is actually over-clocking of the CPU/system and this is NOT guaranteed even though the memory may be fully capable of running at 1600 MHz.

 

http://www.overclockers.com/forums/showthread.php?t=596023

[viro2409]

Thanks for the prompt response.

Okay, the power supply is a beast 850 watts and certified for sli systems.

The Corsair memory is on the qualified vendors list and listed in the manual, and the processor is supported just fine by the motherboard. I'm not sure there would be a problem between them, unless something is defective. I previously tried bumping up the voltage from 1.5 (the default setting) to 1.65 but it still wouldn't work like this. I have yet to try your idea about bumping up the north bridge voltage though.

 

Also, there's one other thing I forgot to mention that's troubling.

The memory wouldn't actually run in dual channel mode. If the two ram sticks are inserted in same color slots on the motherboard (which enables dual channel according to the mobo manual), it won't boot up at all. However, it works in single channel mode with one in a black slot, and one in a blue slot, but only @ 1333 mhz. The motherboard claims to support dual channel 1600, so I don't know what's going on.

[trackrat]

You can check the mobo slots for numbering to be sure you are using the correct two slots for dual channel. As noted in the original reply speed rated RAM needs to be run at the required voltage, i.e. 1.65V on your AMD system. You may need to set the RAM voltage and timings manually in the BIOS as the BIOS will normally set the RAM to default DDR3 voltage and timings, not to the overclocked 1600 MHz. settings.

 

Just because the PSU, CPU and Mobo are designed to run together does not mean that they will run at 1600 MHz. as this is overclocking of the CPU integrated memory controller which AMD only rates to operate at 1333 MHz. on AM3 CPUs. Manually setting the RAM voltage and timings may fix your problem and it may not depending on the CPU memory controller's capability.