Ok, little update. Today I got my hands on a 2x2gb Kingston CL5 1,8V KVR800D2E5K2/4G ram, no problems at all with it when I ran with just this two sticks, then tried with adding one stick of old ram, nothing happens, won't even boot to bios, no sound bips, no picture. Tried with both sticks of new ram and both of old, again nothing. Then, when I tried with just new ram same thing as with all sticks, nothing, removed battery for 5 minutes, put it back and still nothing. At that time I thought, frack, I managed to destroy mobo
As a precaution i removed power supply cable, bios battery and left it like that for an hour and it finally woke up just couple of minutes ago, what a relief
Nothing to add about old ram, it just simply doesn't work on this mobo with this proc so in a few days I'm gonna return it to the shop, I do expect that they will replace it with some other brand, I don't even care if it's the cheapest ram available
Oh, never mentioned before, I just love gigabyte hd5570, won't even get warm under heavy heavy load, actually never heard vent, really good job with that one