Possible incompatibility of my CMZ16GX3M2A1866C9

I bought these modules along with the GA-Z77X-UD3H board (everything is in my specs), and have been fighting some random errors for quite some time.

I am primarily using Prime95 for stress-testing since over years I found it to be the only realiable way to make really sure (Memtest would often pass on me without errors even after numerous passes, and Prime95 would throw out an error in less than 30 minutes).

Does anyone here else have this or very similar setup?

The biggest problem seems to be absolute incompatibility with XMP profile on the board I have. No matter how I'd play with voltages, I'd get errors rather fast (under an hour). It improved significantly after I set timings and speed manually. It's still not 100% though. Really weird.

Is it somehow possible my board simply doesn't like this memory?

Have you ever updated the BIOS? If not please do so, then clear your CMOS and try XMP again.. You may also need to set the memory voltage to 1.55v or even 1.6v if need be.

If you have already covered this then please test each module one stick at a time in the first slot with memtest86+ to be sure you don't have a failing module.

I tried with both the latest official and latest beta BIOSes with exactly the same result. I wish I could get Gigabyte to test it somehow :(

1.55V? I am not sure about that. The memory is spec'ed to 1.5V and I don't see a reason to push it further. I will test it though just for the sake of an argument (after all, if it would "fix" it I'd be most happy)

Memtest passes without problems, but I don't take that program seriously. Like I said, Prime95 would still give me errors where Memtest wouldn't report any.

1.55V? I am not sure about that. The memory is spec'ed to 1.5V and I don't see a reason to push it further. I will test it though just for the sake of an argument (after all, if it would "fix" it I'd be most happy)

The modules wil handle up to 2.0v before damaging thememory. However you would daage your CPU long before you hit that much voltage.

I am positive that tis is the correct move. Most MB's have a tendancy to undervolt the memory and adding just a little to the voltage often regains stability.

I wouldn't have suggested it if it wasn't safe.

Memtest passes without problems, but I don't take that program seriously. Like I said, Prime95 would still give me errors where Memtest wouldn't report any.

Then it could be either MB or CPu related. Memtest is the only program Corsair suggests to use to test memory with.

Well, I honestly have no idea what could be the root of the problem here, but I will try the increased voltage first.

It shouldn't be CPU related at all, I even went as far as loading optimized defaults and testing with that.

Guess I will know more tomorrow (or not).

I have a question about this particular memory.

When I enable the XMP profile, I see two values I don't understand: "profile DDR voltage" and "profile VTT voltage". What's the deal with this?

Wait, what overclock? I am not overclocking my memory at all.

Also, VTT is not memory controller at all, which confuses me even more.

Vtt/VCCIO:

Available starting with the second-generation Core i CPUs (“Sandy Bridge”), this voltage is used for feeding all input/output (I/O) pins of the CPU, except memory-related pins. On CPUs that have this voltage, it is also used to feed the thermal control bus (PECI, Platform Environmental Control Interface).

The default value is 1.050V (that would in fact correspond with non-XMP value)

What I believe memory controller is:

IMC/VCCSA:

Starting with the second-generation Core i processors (“Sandy Bridge”), the VTT voltage was renamed to VCCSA, and is called “system agent.” It feeds the integrated PCI Express controller, memory controller, and display engine (i.e., the “2D” part of the graphics engine).

Default value is 0.925V.

I honestly don't know what to make of XMP at all.

Judging by http://forums.tweaktown.com/gigabyte/48359-ivy-bridge-overclocking-guide-extreme-ln2-section-guide-included.html, I wouldn't want to mess with VTT, seeing Intel's max recommended value is 1.08V.

Wait, what overclock? I am not overclocking my memory at all.

Sure you are! Your CPU only suppports a max of 1600mhz memory so when you enable the XMP profile you are overclocking the memory to 1866mhz.

Depending on the MB memory controller voltage could be named differently. Even if VTT is CPU related it's not uncommon for CPU voltage to be boosted to overclock the memory.

Your running Ivybridge and not Sandy bridge whichh have different BIOS settings. depending on the board.

I honestly don't know what to make of XMP at all.

Judging by http://forums.tweaktown.com/gigabyte...-included.html, I wouldn't want to mess with VTT, seeing Intel's max recommended value is 1.08V.

Correct, but if your overclocking that is the risk you take. You will have to set some values higher than Intels recommended MAX, but it doesn't mean it isn't safe.

From your owners manual:

&

Profile DDR Voltage

When using a non-XMP memory module or

Extreme Memory Profile (X.M.P.)

is set to

Disabled

, this item

will display as

1.50V

. When

Extreme Memory Profile (X.M.P.)

is set to

Profile1

or

Profile2

, this item will

display the value based on the SPD data on the XMP memory

So does the "profile VTT voltage" tell me which value should I set as "CPU VTT" here or not?

edit: I found this thread, which is about exactly the same thing, but the answer is useless :(

So does the "profile VTT voltage" tell me which value should I set as "CPU VTT" here or not?

I don't quite understand what your asking. You could enable XMP and see what the value changes to.

DId you try raising the DIMM voltage to 1.55 or 1.6v as I suggested earlier in this thread? What were the results?

edit: I found this thread, which is about exactly the same thing, but the answer is useless :(

This is sandy bridge platform and not Ivybridge which are different. so it would be irrelevant in your case.

I don't quite understand what your asking. You could enable XMP and see what the value changes to.

Ok, let's try with pictures, that will be less confusing.

(these are not from my system, I took them from a review somewhere)

I know what the values change to, I just don't understand what they mean and what should I do.

http://img818.imageshack.us/img818/2253/memoryv.png

vs

http://img805.imageshack.us/img805/8760/40820341.jpg

DId you try raising the DIMM voltage to 1.55 or 1.6v as I suggested earlier in this thread? What were the results?

Yes, no change.

As I suggested earlier the Profile VTT is going to be memory controller related on YOUR mb. Just leave that one alone or to what ever XMP is setting it to.

You could also change IMC to 1.1v and see if that helps any. If not, then change it back to auto.

If not I would return the kit or RMA it just to rule it out. But since the memory passes memtest I still think this is board related. But stranger things have happened.

I am afraid we're not quite connecting :P

IMC=memory controller voltage.

I hope the RAM guy will step in and clarify this when Easter is over :)

I am afraid we're not quite connecting :P

 

IMC=memory controller voltage.

 

I hope the RAM guy will step in and clarify this when Easter is over :)

I understand exactly what your seeing and saying. But what I am saying is that there are more than one setting that has to do with the memory controller. And what those settings are differ from MB to to MB and also differ across manufacturers.

As i said before if you want to exchange the memory to try another kit that would be fine. But when you enable XMP it sets all necessary voltages for the overclock. And that is what XMP is. It's a one click method for overclocking memory. It will set timings DIMM voltage , adjust memory controller voltage any any other necessary voltages that are needed.

Bottom line is that 1866mhz is such a small overclock for your system it should be able to sustain that easily without any other BIOS tweaks or having to add extra voltage other than what XMP is setting them to.

Your sticks pass memtest which would suggest the memory is fine and that your issues lie elsewhere. But swapping out the memory would be about the only way to really narrow down your trouble.

EDIT: what you can do is also make sure XMP is setting the timings correctly for 1866mhz. They would be 9-10-9-27. Also as i stated you could try adding to the IMC voltage and see if that has any affect! If not just set it back to auto. . You didn't say if that helped or not, so just thought i would see if it did just to cover all bases.

Aha. I see what you mean.

I wish I knew where the heck the memory controller voltage option was hidden in the BIOS, then. Surely it must be possible to control it manually.

When you say overclocking, do you mean relatively to what Ivy Bridge CPU officially supports as maximum speed? I hope so, because the memory itself is guaranteed to work at 1866MHz by default, meaning not overclocked at all.

When you say overclocking, do you mean only relatively to what Ivy Bridge CPU officially support as maximum speed? I hope so, because the memory itself is guaranteed to work at 1866MHz by default, meaning not overclocked at all.

Yes and no. You are overclocking the CPu's memory controller by running 1866mhz memory. Which is basically a memory overclock.

Memory can be guaranteed to run at a certain speed , but it will still be dependent on the strength or weakness of your CPU's memory controller.

For example only , your MB may support memory up to 2133mhz and the memory itself may be "certified" to run at 2133mhz but if your CPU doesn't overclock well, you may not be able to run 2133mhz memory , no matter what you do with BIOS settings. When you overclock at any level , whether it's XMP or you learn how to do it manually in the BIOS there are no guarantees. Also overclocking in general voids CPU warranties because you are running the CPU outside of Intels max recommended specs.

People see these fast modules and see other people using them and don't understand that this is performance enthusiast memory ,not stock parts. And using them often requires you to use settings outside of manufacturers specs.

EDIT: what you can do is also make sure XMP is setting the timings correctly for 1866mhz. They would be 9-10-9-27. Also as i stated you could try adding to the IMC voltage and see if that has any affect! If not just set it back to auto. . You didn't say if that helped or not, so just thought i would see if it did just to cover all bases.

But in your case 1866mhs is really a small overclock for your CPU's memory controller and should run with XMP enabled easily. And again, with a passing memtest, it would suggest you have other problems somewhere else.

So it seems I just had to raise IMC (VCCSA) voltage a bit. So far it seems stable, at least at default CPU speeds. For that (with XMP enabled) I found the lowest stable (~20 hours of Prime95) voltage to be 0.960V (default being 0.925V).

When I switched back to my usual 4.2GHz overclock though, the same thing produced an error in less than 30 minutes. I raised the voltage to 0.970V, and so far Prime95 has been running for a bit over 3 hours - and I hope it will continue to do so.

No problem.

Can you comment on the "profile vtt voltage" value I can see in the XMP though? Is it the same as "cpu vtt voltage" or not?