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RAM disappearing when overclocking

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November 18, 2011 8:37:11 PM

A few months back I built a new PC knowing I wanted to learn the basics of overclocking. I haven't had any issues OCing my CPU, but my RAM has been one big headache. The gist of the issue is that when I push the RAM past about 1650 MHz, my PC only sees 2 GB instead of the installed 4 GB. Here's my setup:

RAM: F3-16000CL6D-4GBPIS
Mobo: MSI 890FXA-GD70
CPU: AMD Phenom II X4 970 BE (yea I know, there's no chance of running RAM at 2000 MHz with this processor, this is a learning process).
Windows 7 Ultimate x64

I realize now I'd have been better of getting a better CPU and spending less on the RAM, but I still want to get the most out of what I have. From what I've read, I should be able to get to 1800-1900 MHz on the Deneb (C3) IMC. I should certainly be able to get more than 1650 MHz. I've done tons of reading trying to figure out how to OC RAM and see where I'm going wrong, but I need some expert help on this one.

The basic process I've been following is:
Increase the FSB
Keep the CPU near stock speed via the multiplier
Bump up the CPU-NB Voltage when RAM disappears.

Obviously this isn't doing the trick. Things go well until 1650 MHz or so, then no matter what I bump the CPU-NB Voltage to, I can't get all the RAM to show up again.

There has to be either some option I'm overlooking, or a bad component. Is there something other than just the CPU-NB voltage I should be messing with? Is it possible I have a bad component somewhere? Which component might cause this, and how would I ferret out the problem? This is driving me nuts.

Some of the things I've tried to see if they made any difference:
When I try to OC the RAM, I disable C1E, Cool 'n' Quiet, and automatic power phasing
I've cleaned the contacts on the RAM and blown out the slots with compressed air
I've tried OCing sticks one at a time
I've tried all combinations of slots
I'm keeping the HT Link frequency in the 1800-2200 range
BIOS is the latest version
I checked the CPU pins and reseated it / reapplied thermal compound
Ran 2 passes of Memtest with both sticks in. Zero errors.

Thanks in advance to anyone who is able to walk me through solving this issue.

Here's an image of my BIOS menu (not my settings, just a generic image):


EDIT: So I decided to pull the memory out and swap it with my girlfriends F3-12800CL9D-4GBRL. I get the exact same behavior from her RAM. Around 1650 MHz it just starts disappearing. By setting it to Ganged I could get it to quit disappearing, but I can't get it to post after about 1670 MHz. Tried adjusting the CPU-NB Voltage, DRAM Voltage, and both. Even more interesting, I've already got my RAM up to 1700 MHz with just about no effort at all on her PC. Ironically, her PC is inferior:

GIGABYTE GA-MA790GPT-UD3H
AMD Athlon II X2 250 Regor 3.0GHz
Windows 7 Ultimate x64

So now I know it has nothing to do with the RAM. I guess that leaves the CPU, mobo, PSU, or BIOS settings as possible culprits. Anyway to narrow it down before I start swapping out components? (Luckily they're both AM3/DDR3 so at least I have that option).
November 19, 2011 5:41:08 AM

Phew. Spent the better part of the night swapping components around to narrow down the cause. It's definitely the motherboard. I swapped the PSU, RAM, and CPU in the two computers and my PC still had the disappearing RAM issue, while my girlfriends PC worked just fine. I actually OCed my RAM to 1740 MHz without much effort, even though her mobo only supports up to 1666 MHz.

So now that I know it's the motherboard, what do I do? There's still the possibility I'm doing something wrong, but I suspect it's a hardware fault. Is there any way to be sure? I'm going to contact MSI again and see what they say about the issue and ask whether an RMA is possible, but I'm interested in the advice of others as well.
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a b } Memory
a b K Overclocking
a b à CPUs
November 19, 2011 7:45:55 AM

the Phenom 2s memory controller is technically only 1333MHz, so you are overclocking that as well. i know you swapped CPUs, its possible it just doesn't want to go higher with your motherboard. mine.wont go past 1580. 1650 is perfectly reasonable. you could try relaxing the memory timings. or giving it dome extra juice on the voltage, in case you'd board.is aiming low.

anyway you have a multiplier unlocked.processor, there's really no reason to worry about that extra little bit on the memory frequency, its much easier to just use that.
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November 19, 2011 5:37:05 PM

Thanks for the input. Indeed I've tried relaxing the timings quite far and every combination of voltage increases. Neither make much of a difference at all (I can push the RAM to 1.7 V and the CPU-NB to 1.3 V and still only get 1 more increment out of the FSB). That's actually one of the reasons I think something is actually wrong with the board. I'm not even able to push my DRAM frequency to the point that I even need to increase the voltages. RAM starts disappearing long before that. I'm actually at stock voltages for everything currently.

The motherboard was one of the best overclocking boards available when I bought it, so it seems somewhat unlikely that it's just crapping out that fast. Likewise I know the Deneb IMC can hit 1800 MHz. Hell, I got the Regor to 1700 MHz. Also, the motherboard and CPU are both fairly popular, so there have been lots of people with the same or very similar setups. It seems like there would be information available on this problem if it were simply the motherboard and CPU not getting along.

Of course, I'm not saying you're wrong, it's certainly a possibility. I just don't think I've really ruled out the alternatives yet.

I'm not really doing this for the performance boost, I know how small of an effect it will have. It's just a learning process. I want to learn the ins and outs of overclocking and it bugs me when I don't understand something.
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a b } Memory
a b K Overclocking
a b à CPUs
November 27, 2011 4:14:40 AM

Have you tried to adjust the ratio's as well? The cpu-nb and the fsb-dram ratios. The fsb/dram ratio should be double what the memory speed is. I sure would like to know what the Memory-Z and advance Dram configurations have in them. Can you get a photo of them as well? Usually you will also need to increase the cpu/pll voltage and the qpi/vtt voltage. And I would disable dram/pci frequency.
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November 27, 2011 4:34:01 AM

I did play with the ratios, some. I tried FSB:D RAM ratios of 1:3.33 and 1:4 with CPU-NB ratios of 1:10 and (probably) 1:12 respectively. I can't remember if the CPU-NB ratio goes that high, so it may have been on 1:10 when using 1:4. I read in several places that the Phenom II IMCs like to have the CPU-NB frequency 3 times that DRAM frequency, so that's what I stuck to most of the time. I only messed with the DDR VTT and CPU PLL Voltages a little, since I didn't see them mentioned much when reading about how to overclock RAM. I did try increasing them slightly at least a couple times to see if they helped.

After posting on a few forums and talking to MSI's tech support, there seemed to be a consensus that the board was defective. It's in the mail atm. Hopefully the new board doesn't have any issues. I'm fairly certain I was doing everything right, as I got a great overclock when I slapped all my components into my girlfriends (cheap) motherboard.

Here's the advanced DRAM menu:


Choosing Linked or Unlinked for DRAM Timing Mode reveals all the usual timings. I don't believe the last two options were available on my board.

Memory-Z just shows the timing tables for the currently installed RAM.
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