System only detecting 12 out of 16GB

[haticK]

I overclocked my CPU the other day (running at 125 BCLK, multiplier of 34, 1.30v) and did a stress test and had no problems. Now I'm trying to overclock my memory and my computer is only detecting 12GB and not all 16GB (shows 12GB in system information as well as in the BIOS). This seems to only happen when I manually adjust the timings (or use the XMP profile), but leaving them set to auto it detects all 16GB regardless of what I change the freq/voltages to. Currently the changes I've made related to the memory are 1.25v (default is 1.2) and a frequency of 2750MHz (default is 2666MHz). The SA/Uncore voltages are currently set to auto and run at about 1.20 (SA) and 1.15 (Uncore), so I don't think that is the issue.

When I set my timings to Auto, CPU-Z shows the timings as 17-17-17-39 (@ 2750MHz) which I would prefer to get to at least 15-15-15-35. I can't get the timings that low on auto unless I drop to ~2133MHz. Another thing I noticed, if this matters, is when it detects 12GB, CPU-Z shows the memory in slots 1/2/3/4 and when it detects 16GB it shows slots 1/3/5/7. I've also tried swapping sticks 1/5 and 3/7 and that made no difference.

Specs:
Intel Core i7-5930k (Overclocked @ 4.25GHz)
Asetek 590LX w/ 6 Fans
Asus Rampage V Extreme
16GB GSkill Ripjaws 4 2666MHz
Corsair RM1000
EVGA GeForce GTX 970 FTW
Windows 10 Pro 64bit

 

[Nebulous]

Check each stick using memtest @ stock speeds. Also overclocking BCLK is useless as gains are minimal at best. Cpu clock speed is king.

 

[haticK]

Check each stick using memtest @ stock speeds. Also overclocking BCLK is useless as gains are minimal at best. Cpu clock speed is king.

So do you recommend I just use 100 BCLK with 42 or 43 as a multiplier?

 

[Woomack]

1. Use 100 bclk as it's easier to stabilize but you have to know that working memory ratios are only 2133, 2200, 2400, 2666, 3000 and 3200. To make it work @2800 you have to use 127.3MHz bclk.
2. Depends from memory it can be on Samsung or Hynix IC. For Hynix here is my thread with results -> http://www.overclockers.com/forums/...pjaws4-4x4GB-DDR4-2666-CL15-F4-2666C15Q-16GRR , for Samsung I have only review with 2800 kit -> http://www.overclockers.com/g-skill-ripjaws-4-16gb-ddr4-2800-cl16-1-2v-memory-kit-review/
3. Generally I would set SA to 1.0V, memory voltage to 1.35V and then try to OC. Or even better 1.4V memory clock and when you stabilize memory then try to lower it. 2800+ in most cases require ~1.25-1.30V. 3000+ usually requires 1.35V.
4. Check max clock at timings of 16-16-16 or 16-17-17. When you stabilize max clock then try to lower timings.
5. Check the latest BIOS

No more ideas right now.

If you know what memory chips are inside ( actually only need brand ) then you can compare settings to some kits from my thread -> http://www.overclockers.com/forums/showthread.php/732290-Woomack-s-memory-test-list , DDR4 kits are on the bottom of the 1st post.

 

[haticK]

Thanks, I'll try some of the settings in your reviews and see what happens. I just don't understand why it's only detecting 12GB when I try to manually adjust the timings. Even if I manually set the exact same timings as Auto would use, it won't detect all 16GB. I don't know if one of my sticks just isn't as good as the others or what. And I am on the most recent BIOS already.

Is there an easy way to determine what memory chips are inside? Can I look it up by a serial number?
It's 16GB (4x4GB) GSkill Ripjaws 4 2666MHz

Edit: This is what happens when I use the XMP profile (below) or manually set timings.





Notice it says Triple


When I scroll through the slots, it shows RAM located in 1-4 but it should show 1/3/5/7

 

[Woomack]

If it sees 12GB instead of 16GB then it can be:
1. problem with memory settings ( usually some sub timings )
2. too low memory voltage
3. problems with memory slot
4. problems with CPU socket and general connection between CPU ( memory controller ) and memory slot

Usually it's 1 or 2 problem.

To check what memory IC is inside all you have to do is to look at serial number. If it says xxxx3400xxx... then it's Hynix. If there is xxxx3500... then it's Samsung. The latest Samsung kits have also something like xxxxA500...

Here is example



144334002804305 <- Hynix

 

[haticK]

Being that I'm using XMP can it really be sub timings? I thought XMP profiles should always work. I also just tried with CPU and DRAM voltage at 1.40 just to see if it would show all the memory and it still doesn't using XMP. Can't imagine I would need it higher than that.

Is it possible to use slots 2/4/6/8 on the mobo instead of 1/3/5/7 incase one of those is bad? Checked serial and it is Hynix, thanks.

 

[Woomack]

XMP is only profile for one clock. At this guaranteed clock it's setting correct main and sub timings. However at higher clock XMP is not working right. Better is to set manual settings and keep sub timings at auto.

Best is to use recommended slots starting from one marked as 1. On all motherboards it's 2 and 4 slot counting from CPU side.

If it's Hynix then I already gave you link for the same memory kit so there you can find some settings with additional timings.
I think you can make it work @3000 15-15-15-35 or 15-16-16-35 Command rate 1N , tRFC ~320 1.35-1.40V.

I'm not sure how to help you more with that missing memory stick issue. On my RVE I had often missing memory but after overclocking at 3200 or higher clock. Sometimes I had to change memory settings or switch memory sticks in slots.