2 * (2*8 GB) = 32 GB Vengeance Pro DDR3-2400 on Asus P8Z77-v Deluxe only runs at 1333

[SSDDRR]

Dear Sirs/Madams,

 

I have two sets of paired Vengeance Pro 2400 (CMY16GX3M2A2400C11A), what results in 32 GB, 4 * 8 GB planks.

 

Those four planks are set into Asus P8Z77-V Deluxe mainboard, which supports DDR3 up to 2800 MHz. Unfortunately, the mainboard does not explicitly list this Corsair memory on official support page in the

latest DRAM QVL list from June of 2014.

 

So by default my PC starts with just DDR3-1333 mode (667 MHz * 2).

 

However, the mainboard supports XMP 1.3, so I switched to XMP mode in BIOS, set the speed to 2400 MHz (1200 * 2), 11-13-13-31 timings and raised memory voltage to 1.65V -- as recommended on the Corsair's official page for that. This is nominal speed for this memory, not some crazy overclocking, so I hoped it will work.

 

But this alone was not enough because PC failed to start with those settings. Then I launched CPU-Z utility and it indicated that for 2400 MHz speeds there is value "44" to be set for additional timing called "tRC"; I could not find this specific timing in my BIOS, so I did not set it.

 

CPU-Z also indicates another parameter to be set -- "Command Rate", which for 2400 MHz speeds shows value "1T". By default in my BIOS this parameter was set to "2", so I changed it to "1" (or maybe I should try to set it to "1T", but I could not; I do not know what "T" is, and why). This did not help either, PC still failed to start.

 

Is there a way to force my mainboard to accept the memory?

 

Maybe if I find this "tRC" timing and set its value to "44", it will help? How this "tRC" timing might be called/renamed in BIOS?

 

Or maybe additional timings have to be set to specific values? The BIOS offers incredible number of secondary and tertiary timings, but I have no idea what to set there. CPU-Z does not show any more information, let alone Corsair page for this memory set.

 

Thank you in advance.

[emissary42]

So by default my PC starts with just DDR3-1333 mode (667 MHz * 2).

That is normal. By default the MB will boot at standard speed until the XMP is enabled.

 

However, the mainboard supports XMP 1.3, so I switched XMP mode on in BIOS, set the speed to 2400 MHz (1200 * 2), 11-13-13-31 timings and raised memory voltage to 1.65V -- as recommended in Corsair official page.

When you enable the XMP, you should not have to manually set timings and voltages. It is possible that your manual timings overruled the timings provided in the memories XMP and that contains secondary timings as well (that you did not set and the board might fail to automatically train). So in the UEFI maybe just load defaults again, then enable the XMP and see if that works.

 

If you still run into trouble, you may want to try this with only one of your kits installed. The XMP is for one kit only and mixing kits can be hit and miss even with two kits of the same model (like different IC versions not playing nice with each other).

 

Then I launched CPU-Z utility that has shown that for 2400 MHz speeds there is value "44" to be set for additional timing called "tRC". I could not find this specific timing in my BIOS, so I did not set it.

tRC is a AMD specific timing and is not available on Intel systems, so don't worry about that.

 

CPU-Z also shows another parameter to set -- "Command Rate", which for 2400 MHz speeds shows value "1T".

This probably is a readout error on CPU-Z's side, the command rate usually is 2T for the XMP.

 

BIOS offers incredible number of secondary and tertiary timings, but I have no idea what to set there. CPU-Z does not show any more information, let alone Corsair page for this memory.

The tertiary timings the MB usually trains by itself. If what i explained above does not work, you can try to manually set primary and secondary timings and manually adjust the voltages (Vdimm -> memory, plus if needed VCCSA/VCCIO -> IMC related).

 

You can get the secondaries from the XMP via Aida64 > Motherboard > SPD.

 

::pirate::

[SSDDRR]

Thanks, I tried that: set all parameters to Auto in XMP mode, but it still did not work.

 

Are tricks for this available? Or maybe a way to understand why exactly the motherboard can not start up with those timings? Maybe some concrete timings or other parameter is an issue? Can it somehow be "debugged" so I could understand why exactly my motherboard does not want to run this memory at 2400 MHz?

[HOODedAssault]

Can u boot into bios with these settings or does it completely fail to post when you enable xmp 2400mhz ? If you can get into bios check vccio voltage. This is memory controller voltage. May need to be between 1.1v-1.2v for 2400mhz. 4 sticks may need closer to 1.2v. On some p8z77 boards the vccio and vccsa are combined into 1 setting called vccsa because intel recommends increasing them together. Even tho that's completely unecessary lol.

[SSDDRR]

Unfortunately, the motherboard completely fails, even reset button is not working. Only total shut down (long press on power-on button) and then turning on makes the motherboard switching to 1333 MHz and showing a message that "overclocking" failed (though I am not trying to overlock anything), "press F1 to enter setup".

 

Since I can not enter BIOS with 2400MHz mode, should I manually set up the memory controller voltage to 1.2V in the XMP mode and see what happens? I will try and write back; thanks.

[HOODedAssault]

Ya give it a sho and see what happens. Next thing I'd try is swapping the kits around like move the sticks from slots 2 and 4 to slots 1 and 3 and vice versa. Seams weird but sometimes when mixing kits they don't want to play well in a certain orientation.