Z97 Sabertooth MKI - Won't POST with 4x8GB?

[Randyman...]

Hello,

I was looking to upgrade my Asus Z97 Sabertooth MKI with a 4970K from 2x8GB DDR3 to 4x8GB DDR3 (32GB). I have two sets of Crucial Ballistics Tactical RAM. A single set worked fine for over a year - never a crash or any instabilities. I can get it to post with 3x sticks, but as soon as I add the 4th stick it goes into a continuous reboot loop (never POSTs / MemOK light lit red - pressing it doesn't help). I'm 99% sure I initially had my old 4x4GB G-Skill in this same MoBo and it worked with all 4 slots.

I loosened timings to 9-9-9-24/2T @ 1333 and juiced it up to 1.65v or a hair above and still no POST (XMP = 8-8-8-24/2T @ 1600 / 1.5v). Bclk is stock @ 100. I got it to post ONCE by placing the two older sticks in the same channel and the two newer sticks in the same channel - but only POST'd once. All sticks appear to be good as it will POST with any combo of sticks as long as I don't add the 4th stick.

Any pointers here? I know the RAM is not on the QVL - but I'm betting I can get it to work with a little help in the right direction. This system has been so stable with a mild OC that I haven't dug deep into OC'ing and RAM tweaking on the Z97! My X79 Sabertooth system didn't seem to be so finicky with 4 sticks (but uses a 4-Channel DDR3 controller, and is only running 4x2GB sticks!).

Thanks in advance for your help

 

[EarthDog]

Tried a BIOS update on the board?

Try raising the System Agent voltage?

 

[Randyman...]

Thanks EarthDog - I haven't been around OCF too much lately - but good to see you're still here

I'm current on BIOS. I'll look into the System Agent voltage when I get home and give it another shot - What's the safe range for that increase (and what does it power?).

Thanks again...

 

[EarthDog]

Thanks! Welcome back!

System Agent voltage goes to the IMC (Integrated Memory Controller)

 

[Randyman...]

Cool - I could see the IMC needing a little bump driving all of that RAM! What is the safe voltage range for the System Agent voltage? I think mine is currently set to "Auto"...

Will report back later once I give it a whirl (still at work ). Rock on!

 

[EarthDog]

Oops... try giving it .1-.15V more and see what it does.

 

[Johan45]

It'a also always a good idea to clear the CMOS when changing the ram set-up.

 

[bob4933]

Running the same board, 4x8 wasn't an issue for me. I had it runinng in xmp with no added voltage.
I dont think underclocking is going to net you stability you should already have. I would recommend testing each DIMM individually and seeing if you have any issues with it.

Worse comes to worse, you have a 5 year warranty on that puppy, get it RMA'd if its not working.