Is my motherboard broken?

Hi, I'm new to this forum.
Well, I have a problem with my rig and since I built it using guides from this site, I thought maybe I could find some help here

Here are my rig's specs:

Intel i7 920 @ 2,66Ghz
Gigabyte EX58-UD3R
3 x 2GB Kingston DDR3 1333
Sapphire ati 4850x2
Western Digital HDD 500GB caviar black
700w power supply
Windows Vista x64 sp1

My problem is this:
I want to use all my ram in triple channel, but whenever I use the second memory slot I keep getting blue screens randomly.
I'm using prime95 to test it. I've tried using the first and last slots only and then it works fine, but when I place any ram module in the second slot it crashes almost instantly after beggining the test. And If I let it crash many times the system won't boot and I have to unplug it for a while to make it boot again.

But there is more. After checking that, I was almost certain that the problem was that slot, but yesterday I was using the Hammer editor (hl2's source sdk game editor) and it crashed without using that slot.

Is that slot faulty? could it be any other problem? and could that last error have nothing to do with it at all?
I have all the minidumps that the system created on those crashes but I can't figure anything with them.

Any help would be very much apreciated.

Best regards

Hi, thanks for the reply.

There is one interesting bit about that, because in the bios, the ram timings are automatically set to 1066, latency 7, and my ram factory specs are 1333, latency 9. The voltage is 1.5v and that's not changed I think.

How can I change it, and what timings should I set?

Thank you very much for your assistance, sadly, I'll have to wait to try that out (I'm not at home right now) But I will as soon as I can

One more thing, should I trust the info about the memory that I can get from EasyTune6?

Hello again, I changed the timings as specified by the manufacturer and ran a test. It seems to be working flawlessly now, with every module installed using triple channel

Thank you very much for your assistance, if it wasn't for your advise I'd probably had returned the mobo.

Hope this helps other people with the same problem.