12GB Viper Series Problems

[XD-3]

Hi All,

So I have 12GB of Patriot Viper PC3-12800 (1600MHz) which I purchased as part of a new system (Received on the 20th)...

I've been testing the system and I cannot get the memory stable at 1600MHz using the X.M.P profile, each stick will run correctly on its own stable and each set of three will run correctly at the specified speed using X.M.P.

However when running 12GB in all six slots I will receive memory errors and the system will not always detect 12GB but instead detect 8GB. This lead me to test each stick individually as mentioned above.

Currently I have them running at 1333MHz at 7.7.7.27 1N (1T) which I guess I am not to fused about, but just wondering what you guys think I should do here with regard to the settings or returning the memory for replacement?

Under X.M.P the memory should run at:

-8.8.8.24 2N (2T)
-1.65v -(Defaults to 1.66 in Bios)
-3200MHz -(DRAM/QPi Link - double the memory speed)
-133 -(BCLK I Think)
-100 -(PCI-E Link)

I have tried increasing the QPI/DRAM Voltage to 2.3000V from 2.25000, but I am a little concerned about increasing the DRAM Bus Voltage because of the 1.65v limit on Core i7 CPUs. It has also crossed my mind that the motherboard just does not like 12GB at 1600MHz and perhaps a future Bios update will fix the problem with the bios being relatively new and the sticks achieving the correct speed individually...

What do you guys think
XD-3

Other Specs
-3.06GHz 950 i7
-Asus P6T7 WS Super Computer Board
-1000W Corsair HX
-4890 XFire

 

[Firegod]

Motherboards have never liked all their slots filled with high density memory. It puts more strain on the controller. Be this on the Motherboard or built-in to the CPU. As you've found out, each DIMM separately is OK, you have problems with all 12Gb installed.

My thinking would be a RAM option (one of those awkward advanced timings), voltage issue, or BIOS.

 

[Venares]

With 12GB you probbly need more volts on the QPI.

 

[XD-3]

With 12GB you probbly need more volts on the QPI.

Intel specifies 1.35v max on the QPI, so I guess to be INSIDE the safe margin you should run 1.2v - 1.34v and similarly for DDR3 DIMMS the absolute max is 1.875v acording to the Intel white paper, so 1.5v - 1.874v.

mmm I wish they where more specific about these things.

XD-3

 

[Xelene]

You wont notice any benefits running them at 1600MHz anyway - the triple channel allows for enough bandwidth at lower clock speeds - and slowing them down allows (as you've seen) tighter timings. All the articles & benchmarks i've read have said 1333 is the sweet spot in terms of throughput vs latency on the i7 - for real world usage.

1333MHz at 7.7.7.27 1N (1T) is pretty good actually!

 

[mmj_uk]

I have a similar problem, my guess it that it's something to do with the CPU memory controller, remember DDR1600 is only unofficially supported.

 

[rjk]

1.325v on qpi for 12gb