Motherboard won't boot with Ram in 3rd and 4th slot

I have the EXACT same problem! Also just got a GA-Z68X-UD3H-B3 with i5-2500K... 1 stick works fine in one of the first 2 slots (labelled DDR3_2 or DDR3_4). Try in a different position, or add a second stick and it powers on and off repeatedly.

I've tried updating the BIOS to the latest version (F10) - no change.

Any help would be appreciated!!  

CPU: intel i5 2500k
PSU: Silverstone 750W
MOBO: GA-Z68X-UD3H-B3
RAM: G.SKILL F3-17000CL9D-8GBXM (2 x 4gb ideally!)

OK, I did a bit more digging on the interwebs, and have fixed the problem (for me, anyway).

LPeezy21: if you are reading the manual that came with your motherboard, my advice would be to throw it in the bin. Or burn it ceremoniously - whichever you prefer. It is useless.

The manual says to put your RAM in the slots labelled DDR3_1/DDR3_2 or DDR3_3/DDR3_4 - which from the left are either the 1st & 3rd, or 2nd & 4th slots.

THIS IS WRONG.

I put my RAM in the first two slots from the left - i.e. DDR3_2 and DDR3_4. It is now working perfectly.

From what others are saying online, it should work fine with all 4 slots occupied, but if you're only using 2 slots, it usually has to be the first two from the left. Apparently this is the way most motherboards are designed to work, so I don't know how they managed to mess up so badly when printing the manual. HOORAY FOR WASTING HOURS OF TIME UNNECESSARILY!!!  

Sorry, but your are only partially right, the board works fine with the Corsair RAM installed in what Gigabyte calls channel B, but it will not work with four sticks installed or with any RAM at all installed in either of the Channel A slots, not even if you just install a single stick of tested and proven RAM.

For some odd reason, the Board BIOS does not seem to recognize Corsair Vengeance RAM in Channel One. Does anyone know of a setting to overcome this?

Thanks

My gigabyte 990fxa-ud3 is doing the same thing. i swapped out my processor from a phenom to an athlon. after changing the processor, i found it would only boot with the memory sticks in the first 2 slots. it runs, however, CPUZ shows it running in single channel. have you checked that? i tried booting with only 1 stick in all 4 slots and it will no boot in the 3rd and 4th slot. when i had the phenom in, i could run the memory in the 1st and 3rd slots or 2nd and 4th slots to get dual channel. now i dont. i have no idea what happened to the 3rd and 4th slots. as near as i can figure, they have died.

You are absolutely right, mine shows that my dual-channel memory is only running in single-channel mode.

More mysteriously Gig's Touch Bios says my DDR3 1600 Ram is running at 1333 while CPUz says the DRAM frequency is only 665.2.

Since that is pretty much exactly half of 1333, I'm assuming that maybe CPUZ is giving me the same number in a different way (I'm not at all expert in CPUZ).

But I don't know for sure and would appreciate someone explaining a few of these mysterious things to me.

As for the original problem with the board no supporting four sticks of RAM, from what I've read the board is simply trash by design. So while it might run correctly if I tried three or four different brands of RAM in it and got lucky, I'm really thinking it might be easier and less frustrating long term to RMA the board while I still can and start over with something that's got a better rep.

Truth is, while this isn't a high-end motherboard, it is far from a low-end one -- anything between $150 and $175 is hardly cheapo in the MB world these days. Therefore the fact that slots three and four aren't compatible with RAM that runs fine in Slots one and two (and vice-versa) is totally unacceptable.

What was the fix for this?
I am having exactly the same problem with a gigabyte ga-z68xp-ud3. The 2 slots closest to the CPU won't work but the two closest to the edge will work (in any combination).

Much appreciated man. ******* hell gigabyte  

Hey sorry for the late reply guys but I ended up returning that board and got a replacement. I actually bought two of them (one for me and one for a friend) and only one of them had that problem so I guess there was something wrong with the board.

I have the same problem!!!! the slot closest to the CPU when occupied doesn't work and turns the computer on and off over and over.

Same exact problem here with a Z77X-DH3...