asus p7p55d evo RAM problem

[grinedin]

I have 2 stick DDR 3 RAM memory (2x2GB) khx1600c9ad3/2g and my PC works fine. Now, when I added one more stick (4GB) khx1600c9d3b1/4G windows can't run. My monitor shows blue screen and then restart.
I have win 7 64 ultimate, CPU i3, VGA GF 750Ti. What's the problem?

 

[GhislainG]

Did you leave voltage on auto or did you increase it? Driving 4 modules is somewhat challenging for that chipset.

 

[grinedin]

I tried to increase the voltage to 1.65 and again the same. I even left only one module of 4GB and again the same. I replaced the memory module into the store thinking it was broken. They gave me a new but still appears blue screen. I do not know if the problem is due to three modules of RAM on the motherboard. With two modules of 2GB everything works great. As soon as I add a third module of 4GB blue screen again. BIOS reports 8GB RAM at 1600Mhz but Win7 won't start.

 

[GhislainG]

The 2GB and 4GB modules don't have the same specs and that leads to stability issues on most motherboards. I don't understand why you didn't buy an 8GB kit; individual modules are not guaranteed to work together (3 obviously is worse than 2). Try to run them at DDR3-1333MHz, timing 9-9-9-24 at 1.5V. Increase voltage a bit if need be, but don't exceed 1.6V. At 1600MHz you need to loosen the timing to 11-11-11.

 

[grinedin]

I tried at 1333 Mhz, timing 9-9-9-24 at 1.5V and I raised to 1.6V and nothing. I do not understand why two 2GB modules are operating normally and when I put only one module of 4GB windows does not work. I am afraid that the problem is in the motherboard. I do not know if it's allowed here posting pictures to get a better insight into my BIOS. Maybe there is something to be set.
In any case, thank you for trying to help me. I'm completely crazy and very annoyed because I think that the problem is solvable but obviously I do not have much knowledge about it.

 

[GhislainG]

You mean the system doesn't work with a single 4GB module? The 4GB module has lower specs than the 2GB modules.

 

[grinedin]

Exactly. The system does not work with one module of 4GB. BIOS reports 4GB of RAM when I put the module of 4GB. However, the system does not work. Only blue screen appears and the PC is restarted. I installed a fresh copy of Win 7. I also restore all settings in the BIOS to default values. The system only works with two modules of 2GB of RAM. I have replaced the module at the store where I bought the RAM memory but still the same problem. They told me that it should be set out in the BIOS. Another option is to take the computer to a service center to test it for a week or two. But because of the job I can not be without a computer for so long. So I really do not know what to do.

 

[GhislainG]

The issue is the 4GB module is dual rank, but your motherboard supports single rank only. Buying a module or kit (much better) that's certified for that motherboard would be best.