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CMD64GX4M8A2400C14 which strap on XMP & X99?


dakotha

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Hello,

 

I would like to go for 64 GB kit of Dominator Platinums on X99. I am wondering if this kit CMD64GX4M8A2400C14 uses 100 or 125 strap? I never want to buy another 125 strap XMP-kit anymore, it just complicates things, but I still like to use XMP so I want 100 strap.

 

Any ideas?

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I can see why you might want to avoid the 125 strap with SLI GPUs. As stated above, this is something you can set in the BIOS settings and must be balanced with your overall overclocks, both CPU and memory. As long as you keep your frequency expectations reasonable, you should be able to run 64GB on the 100 strap in concert with a balanced CPU overclock. 2400 or 2666 should be relatively easy. However, you could also do the same with your current kit. Did you need more memory?
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What strap is used for a specific memory frequency when activating XMP is chosen by the mainboard. Up to DDR4-2666 most X99 models should keep the standard strap, others can even use DDR4-2800/3000/3200 in it.

 

Hmm this is the first time I hear this scenario. I've had a few kits so far and both my 32 GB kits used 125 strap (2666 and 3000). However all my 16 GB kits have used 100 strap (2133, 3000 and 3200). I am confused why the 16 GB 3200 kit would use 100 strap out of the box unless the motherboard does the same for all 16 GB kits, but uses 125 for 32 GB kits. :confused:

 

I can see why you might want to avoid the 125 strap with SLI GPUs. As stated above, this is something you can set in the BIOS settings and must be balanced with your overall overclocks, both CPU and memory. As long as you keep your frequency expectations reasonable, you should be able to run 64GB on the 100 strap in concert with a balanced CPU overclock. 2400 or 2666 should be relatively easy. However, you could also do the same with your current kit. Did you need more memory?

 

How does 125 affect SLI GPUs?

 

The main thing I would like to avoid 125 strap, is because adaptive voltage doesn't work properly with it on my MB, also there are reports of M.2 slot dropping to PCIe 2.0 on 125 strap. Also I have a feeling that there is some kind of compatibility issue with my vBIOS and UEFI when using 125 strap, sometimes I am unable to see the boot screen before Windows even after disabling CSM. That issue only happens at 125 strap...

 

I tried my Dominator Platinum 3000 32 GB kit on 100 strap, but it seems I am not going to get much over 2666 with it. Decisions decisions...

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Raising BCLK can cause synchronization issues with anything in the PCI-E slots, including your M.2 drive. It's commonly referred to as "jitter", although there is no guarantee this is a problem just because you use the 125 strap. The adaptive voltage is a much more convincing reason and I had almost forgotten about that aspect having been on 100 for so long now.

 

In the earlier days of the platform, any time you moved to a memory speed of 2666 or above, the Asus BIOS was programmed to default to the 125 strap. It's purpose is to give you a chance at more stability, with the above mentioned consequences. At some point, I thought they removed this "auto" switching behavior, but either way you can always go back and manually set the strap to 100 and then ensure your multipliers are back where they belong for that value. It is possible the pre-programmed behavior is different between varying models of the Asus X99, but you should be able to manually adjust on all of them.

 

 

I tried my Dominator Platinum 3000 32 GB kit on 100 strap, but it seems I am not going to get much over 2666 with it. Decisions decisions...

 

Does this mean you can't boot at 100 strap/2800+ MHz on the memory? Or setting the speed in the BIOS triggers an automatic jump up to the 125 strap? Since the strap really only increases your chances of stability, the real questions is what frequency can you get to with the 100 strap for a particular amount of memory. As usual, this means you will have to look at the overall overclock as well. I have had minimal difficulty running Corsair Dominator 3200C15 4x4 at 3200 with a slightly tightened timings and 4.4/4.5GHz on the CPU -- 100 strap. However, once you get to 32GB, there is nothing guaranteed about 3200 on the memory. It may not be plug and play. At 64GB, I think you need to temper your expectations. 2400-2666 is a good bet, but I have not used this much memory and I don't know a lot of people who have tried. You'll have to figure out what you really need.

 

I also think you should consider not using the XMP preset for the given speed. Obviously, it is of no value on other speeds, but in my experience I have had much better success allowing the board to choose the secondary and tertiary timings for the given XMP speed, compared to the pre-programmed values on the module. This is specific to the Asus x99 platform. The BIOS does a few other things went you enable the "XMP mode" and I have found undoing them to be more of a nuisance than an assist. Manually tuning those timings would be superior, but that is not something the average user likely wants to do.

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Does this mean you can't boot at 100 strap/2800+ MHz on the memory? Or setting the speed in the BIOS triggers an automatic jump up to the 125 strap? Since the strap really only increases your chances of stability, the real questions is what frequency can you get to with the 100 strap for a particular amount of memory. As usual, this means you will have to look at the overall overclock as well. I have had minimal difficulty running Corsair Dominator 3200C15 4x4 at 3200 with a slightly tightened timings and 4.4/4.5GHz on the CPU -- 100 strap. However, once you get to 32GB, there is nothing guaranteed about 3200 on the memory. It may not be plug and play. At 64GB, I think you need to temper your expectations. 2400-2666 is a good bet, but I have not used this much memory and I don't know a lot of people who have tried. You'll have to figure out what you really need.

 

I also think you should consider not using the XMP preset for the given speed. Obviously, it is of no value on other speeds, but in my experience I have had much better success allowing the board to choose the secondary and tertiary timings for the given XMP speed, compared to the pre-programmed values on the module. This is specific to the Asus x99 platform. The BIOS does a few other things went you enable the "XMP mode" and I have found undoing them to be more of a nuisance than an assist. Manually tuning those timings would be superior, but that is not something the average user likely wants to do.

 

I can boot 3000 only using 125 strap, but only 2800 at 100. But I didn't check for any stability yet at 2800. I think I read that 2800 is not a good memory ratio to use, efficiency-wise. 16 GB seems to be a breeze with my CPU IMC, but 32 GB is completely different story. I'll have to see if I really need 64 GB after all.

 

Thanks a lot for your reply.

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I am not a big proponent of the 2800 speed either. It has been a common sticking point since the beginning and is also the voltage threshold from 1.20 to 1.35 for many kits. It's such a small boost over 2666. I would rather run at that speed with lower voltage and/or better timings.
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