Really incompatible? Asus Z170-P & G.skill CL14

[LTHarper]

Greetings dear community
To be more specific the RAM is G.skill 2x8 GB CL 14-14-14-34 (product number: F4-3200C14D-16GVK )

Apparently I did a mistake buying, as both QVLs from Asus and G.skill mutually exclude these two products from one another. Now, I don't have the RAM and mainboard in my hands yet to actually check it out for myself, it is still shipping in, but all this has brought up more questions than answers.

So apparently it's not about the 3200Mhz but about the CL timings that make it incompatible with the Asus Z170-P. Okay, I can more or less live with that and I'm not going to shed 100+ more bucks for a different mainboard, when I can actually save 30 to 40 bucks in buying compatible ram. So currently windowshopping for alternatives, so I can hopefully order a new kit on Monday. But all that windoshopping makes me doubt a great many things 🙁

Going from the QVL from the Asus board, I'm running into quite a lot of comprehension issues. A link to it so you can see exactly what I mean is here.
In addition, the G.skill version of compatibility for that mainboard goes there. I'm not dead set on g.skill RAM, it's just something to consider as counter-reference.

The idea was to grab a 2x8 Kit now and upgrade with an additional 2x8 kit later, however the compatibility often makes me wonder if that is possible. I don't get any confirmation if I use a 2x8 kit twice if that is actually going to work.

Here is what has me covered in question marks:
First, the g.skill website doesn't have a single 3200+ Mhz stick up there for compatibility, whereas the Asus List has... more than ten. This is only one example of incoherence. What does that tell me now?

In general, I came to think that the faster the frequency and the lower the CL speed, the size of Sticks has to decrease, which is why no really highspeed 2x8GB kits are listed. Still, my biggest confusion goes about bigger kits like 32Gig listed where their smaller counterparts that are otherwise identical are not listed as compatible. That goes against that premise.

Another one is; The Patriot 4x8 GB kit at 16-16-16-36 with 1.35 Volts at 3000Mhz. Why isn't the dot on the far right for 4dimm sockets selected, only for single and dual? I mean the kit is by nature a 4-socket configuration, so what is that all about? Originally I thought that a 2x kit with a dot in the "4 socket" list will mean that the kit can be used twice. But apparently this line of thinking can't hold up if the 4x8 Kit has NO dot in the 4 socket selector? Or does that only refer to single, dual and quad-channel ability for some reason?

Sticking with that example, why is that Patriot 4x8 Kit listed as compatible, but not a "worse" product like G.skill F4-2800C16D 2x8 GB at 1.35 Volt, not to mention the 1.2V version, which should be nicer to handle by all means? Why aren't those listed? How would they not fit the bill and why would they cause compatibility issues or outright refuse the machine to post?

So after a lengthy preface, before I get to the dreaded "TLDR" part, here is another thing to know why this topic actually came to place:
Originally I had carefully planned a system based on a 4790k, however that had to be scrapped overnight and I had to select CPU, Mainboard and RAM on a moment's notice, which is why I ordered RAM that I did not check for verified list. I just narrowed the search to the fastest the board could take comfortably, and went for the lowest timings, not double-checking with the QLV. Which apparently is going to lead me with a non-working computer once the shipping arrived (which should be today, Friday).

So to the TLDR part:
1) Does anyone have experience with the combination of Asus Z170-P and G.skill 2x8 CL14 3200Mhz ? Will they work or not? I mean, will they work for those specs, because I'm sure they can work in some default mode for JEDEC standards to at least boot up... right?
2) How should I interprete the dots in the "dimm socket support" columns?
3) If one 2x8 Kit is verified as "okay", does that also mean I can always slap a second kit into it and expect it to work, despite the weird "dimm socket support" dots missing on the 4 socket column?
4) Can I just go off "baselines" like the best specs for something in a certain category and go like "okay anything similar to that should work?" So, if I see a 2x8 GB CL15 kit work under one speed category with one specific voltage from one brand, can I expect the same stats but a different brand work just as well?

I wanted to ask Asus those questions, but on their contact form they require me to put in the serial number of the motherboard which I don't even own yet, so there goes that. And since they are companies that work business days, I rather thought to give Tom's Hardware a shot with the community being available through the weekend as well

Help would be greatly appreciated, it's been a while since I had to deal with fine details like that, and I'm horribly out of practice 🙁

Thank you all!

 

[Tradesman1]

1. They should work together, your CPU will be the deciding factor as to whether or not you can run at 3200, (may ell take a bit of a CPU OC to run 3200 which is perfectly normal.
2. Believe you are speaking of teste configs
3. There are never any guarantees when mixing sets of DRAM (even of the same identical model), here again in part it will depend on how strong your MC is in the CPU.
4. Generally that is true

In short, if running a K model CPU, you should be fine

 

[LTHarper]

Thanks for the response
To give a little more insight, the rig here is not a dedicated gaming machine, which is why the graphics card might sound a bit underwhelming being a 750 TI. I upgrade that later, seeing how the 10xx series will pan out on the mid tier market. I'm also not a 4K resolution hunter, and I rather turn down details for smoother framerates than salivate over "slideshows"
The rig will be much more used for music / video / sound / image editing and production. This is why I was inclined for a bit higher ram speeds and better timings.

1a) How much CPU overclock would I have to do for the memory to work at 3200? Honestly it's the first time I really went for some higher speed memory, mostly because of the disparity in CL timings and speed vs. DDR3 (and yes I did read up as many benchmarks and real world tests as I could to settle on those)
1b) Looking at the Vendor lists, apparently the speed is not the problem, but the CL timings. So are we talking about running the overclock to get them to work at 3200 or to get them to work with CL14 or both?
1c) How high could I go RAMspeed wise before overclocking my CPU or is that bound to what the baseline is certified with? Because I rather not overclock if I can avoid it. Despite buying a 6700K, I rather went there for the higher guaranteed base speed and the option to overclock later if I really need to.

2) I was pulling a stupid there myself I guess. I looked at the bottom of the sheet and noticed this;

• 4 DIMM: Supports 4 modules inserted into both the blue and black slots as two pairs of Dual-channel memory configuration

So wouldn't that mean the kit I was using as an example is not possible to run in dual channel mode due to the lack of the dot in the 4 DIMM section? Isn't that a bit weird? At this point, how much are these QVLs to trust really?

3) I wasn't talking about mixing sets of RAM, sorry if I made that impression I meant to purchase the same identical kit at the end of the year or so, because I'm pretty sure they will still exist at that time.

4) So if I follow that rule of thumb, and noticing only 15 and 16 CL chips on higher speed in the QVL, meaning that the CL14 will be basically not working? 🙁 Because the best thing I can see there is a CL15 at 3000Mhz.

 

[Tradesman1]

Two sets of the same identical model is 'mixing' as the sticks weren't tested together. Sticks that go into a package are tested to play nice

 

[LTHarper]

Hold on... all those dozens of times in many years with DDR1, DDR2 and DDR3 where I was advising people on their RAM choice in respect to the board they chose to make sure if they want to upgrade, they should still use the same sticks (which they did later)... was just working because dozens of times it was just pure luck...?

The remainder of the points are still valid, so anyone who can shed some light there, it's appreciated.
I'm definitely going to post the results when I have the gear on monday.

 

[Tradesman1]

They might work, and might not, the forums are full of threads of people mixing/trying to mix 2 identical model sets. DDR and DDR2 was a lot more forgiving, but I've gotten identical sets direct from manufacturers that didn't want to play, see items 2 and 6 here:

http://www.tomshardware.com/reviews/ddr-dram-myths,4155.html

 

[LTHarper]

Sorry for taking my time to get back here, I followed some other leads too, including G.skill tech support
That's a great article, thank you for pointing that my way! Funny how I didn't stumble across that with all the different key words and search engines. Oh well!

So adding everything together, I COULD get away with mixing two identical kits of 2x8GB if I do one or many of the following things:

■Increase voltage (not recommended on modules that already run on 1.35V)
■Decrease frequency by one step
■Increase CL timings by one step
■Increase tRFC by... *something*

I put the remainder of my thoughts and ramblings in a spoiler

Spoiler

I have been going through the lists a couple of times now and looked at the "working dual channel with 4 sticks" mode with 4x8 GB kits on the Asus QVL. Then I went to find 2x8 kits which are otherwise identical with their verified 4x8 counterparts, even visually (which to me maybe is a clue there too), but I couldn't find all 2x8 counterparts to their bigger 4x8 cousins. So those are out. I'd like to believe those selected 2x8 kits are more likely to work with an additional set than others, or rather, that the tweaks are less major. But I guess that's just my imagination and a placebo effect when it comes to the identical heatsinks 😀

I also looked into single sticks which are marked to work in all 4 slots with dual channel mode. What's notable here is that these sticks always have worse timings than their paired counterparts, so this again speaks volumes about how they're playing it safe to ensure compatibility.
So could I, for example, grab two single sticks and mess with the timings to see if I can get them a little faster from the "playing it safe" default area. But then that would be in vain when adding two more single sticks. And I guess something tells me those single sticks are not exactly the most stable of them all. "Binning" comes to mind, so I better avoid those single sticks.

What fascinates me the most is how things totally don't make sense in the QVL. Like, for example, a 4x8GB G.skill set with 2800Mhz at 16-16-16-36 works in dual channel when 4 sticks are populated, but a SLOWER 2666Mhz at 16-16-16-36 doesn't? Then again a G.skill 8x8 GB 2800 kit with CL 16-16-16-36 DOES work again? I always find those funny since you can't even fit an 8x8 kit on that mainboard. Totally curious and out there.

The main problem I'm having is that I'm already 150 Euros over budget. Downgrading the ramsticks to 2x8 would free up to 50 bucks depending on how slow I go (2400Mhz being the low-cap). But going for a 4x8 set on slower speed is maybe 10 bucks more , or when wanting to push for higher speeds again I would have to add up to 50.
The other part of the main problem is that I have already purchased everything and so I HAVE to swap out and return the RAM, because I'm not seeing myself adding another 100 for a different motherboard only to successfully use the RAM I have already here *sighs*

Anyways, thanks for all the input

 

[Tradesman1]

The above steps might and often will work when sets don't want to play, but again, no guarantees...additionally there are numerous other secondary and even tertiary timings you can get into, but generally if the 1st three above don't work and adding additional voltage to the MC (memory controller) (a separate voltage from the DRAM voltage) doesn't work then are pretty much out of luck

 

[LTHarper]

Oh man you are making it hard for me to pick a solution to close the topic 😀 but I appreciate all the input heartily.

Last thing; Do the chances increase of making two 2x8 kits work with each other if the base frequency is lower anyway? So is 2666 more likely to play nice than 2800 if they are meant to run on the same timings? Or is that just another case of "it simply doesn't work that way" ?

 

[Tradesman1]

Yes, as a general type thing. If/when you do if any problems give me a shout, DRAM is sort of a specialty of mine 😉

 

[LTHarper]

Adding some more information after coming to terms with G.skill tech support:

So they confirmed to not guarantee the compatibility even between identical kits, which is what was to be expected. They also said as we expected that lower base frequencies have a higher chance of playing nice with each other than higher speeds.
Further it was mentioned how increasing Voltage has the highest chance of making two identical kits work. Next best bet would be lowering frequency. In a nutshell I was told that normally it shouldn't be much of an issue in my speed range (up to 2800Mhz) but they of course cannot guarantee it. Which is what I find curious, as we know the big kits are more expensive. So this wasn't exactly a money grab move, which I appreciate. Especially since they went out of their way to answer my nitpicky questions of "if I do this and that, will it work?"

Speaking about those, here is an interesting part though; the gradual changes with CL and tRFC timings on DDR4 don't really impact stuff as much as it did with DDR3. This is intriguing compared to the information obtained in this topic and the previously linked article. I was also told that the kits are tested to work straight with XMP profiles and no additional CPU overclock. It might have only been related to the 2800Mhz kits and not the 3200 ones.

Just wanted to add this here and see if there is another comment to be taken for it before doing a little summary in the first post before marking it as solved

 

[Tradesman1]

As far as an OC of the CPU goes, depends on the individual CPU ad it's MC some say 6600Ks are stronger than the norm and some are weaker (Silicon lottery) also depends on the CPU, i.e. a 6700K might easily handle 3666 where a 6400 CPU just can't do it

 

[LTHarper]

I see, sure. But as for kits that are sold and advertised as certain speeds, they always will work once they are mentioned in those "qualified vendor lists", correct? So as in your signature, when taking your Z170 board and your 3200Mhz RAM, no CPU overclock would have been needed to get the RAM going at that speeds since it is QVL verified?

 

[Tradesman1]

Not true, the vertising for the board is just that - f mobo - and yes it is capable of rung 3200 (in the specs it typically shows higher data rates as something like 3200 (OC), 3400 (OC) - the OC indicates an OC of the CPU/MC may be required to run that DRAM at that data rate