Problem with Dual Channel

[m45k@gmx.ch]

Hello,

I've just assembled a new system and encountered some RAM problems.
The Specs are:
MB: Gigabyte GA-870A-UD3
CPU: AMD Phenom II X6 1090T Black Edition, 3.2GHz, Socket AM3
RAM: Corsair Vengeance, 2x4GB, DDR3-1600, CMZ8GX3M2A1600C8
VGA: Sapphire HD 6870 1GB, PCI-E x16
PSU: be quiet! STRAIGHT POWER, E8 CM 680W 80plus Silber
Cooler: coolIT ECO, all-in-one Mini-WaCo CPU-Cooler

When i put in both 4GB sticks in the dual-channel sockets, the pc doesn't boot. With only 1 it works, with both of them. I already set the settings according to the specifications (8-8-8-24, 1.5V). I also ran Memtest86 on them separately and both of them kept failing test 7 "Block Move". The only setting that allows me to boot with both sticks installed ist "Channel Interleaving=disabled", although the MB then only detects 1 stick or 4GB.
I know that my RAM isn't on the compatibility list of the Mainboard supplier, but i never had issues with that. I've also seen others with that setting in the net. And shouldn't both sticks work together if they work separately?So i've tried to set the voltage to 1.6, but it didn't work.
So what do you think could be the problem? Defective RAMs? Or incompatibility?
Thank you for your answers.

[Apple.Mac.Rocker]

This clear looks issue of incompatible ram. Channel Interleaving settings are responsible to improve the performance of your memory. But there are certain conditions. The memory module should be of similar configuration, uniform size and place properly with compatible board. If you disable them, then things might work, anyhow in future you will face the same issue. The ram speed also matter here, that is the frequency which must match with each other. Interleaving is responsible to provide balance performance among all the nodes of memory. Getting a proper bios patch can work out.