RAM Slots

[SaSaSushi]

Sorry, but this is one of the examples in that thread that I was talking about.

If you plan on using the stock RAM in conjunction with aftermarket RAM, Ballistix is indeed the wrong RAM. Buying the right RAM means getting the exact match with the exact same timings. It should not matter at all what RAM slot configuration you use, because it will still boot, if you have matched the timings correctly. If you buy one with the wrong timings, in certain machines, setting it up with the wrong DIMM slot configuration will mean the machine may not boot. It has nothing to do with DIMM seating.

Sorry, but you're wrong and since I'm actually using it in combination with the stock RAM in all configurations with zero issues I think I am just a little more qualified to speak to the matter. It has nothing to do with the CAS latency which, by the way, Apple doesn't even mention in their requirements. I'm using the exact same machine as the user you are making these bogus claims to. Not to mention if what you say were true, it wouldn't work for him in any configuration.

I have confirmed by both benchmark results and CPUZ in BootCamp Windows that with both the stock RAM and the Ballistix installed together all modules run at CL17.

However, if you plan on using it WITHOUT the stock RAM, then the Ballistix RAM is fine to use.

I'm going to leave the final judgement on whose correct in this debate to the reader. Are you going to believe the person who is actually using the Ballistix or the other guy?

 

[EugW]

Sorry, but you're wrong and since I'm actually using it in combination with the stock RAM in all configurations with zero issues I think I am just a little more qualified to speak to the matter. It has nothing to do with the CAS latency which, by the way, Apple doesn't even mention in their requirements. I'm using the exact same machine as the user you are making these bogus claims to. Not to mention if what you say were true, it wouldn't work for him in any configuration.

The bolded statement is not necessarily accurate. This is actually the specific issue I'm talking about, and it sometimes happens with Macs. Mismatched memory doesn't boot. Change the configuration, and then it boots. Change it back, and it doesn't boot. However, it depends on the specific machine, and it depends on the specific specs of the memory purchased.

JVNeurmann's results are a good illustration of this. It works for you? Great. Be happy that it does, but don't discount JVNeurmann's experience just because it's working for you.

The point is it doesn't for JVNeurmann in a specific configuration, and that should not be a surprise because it is known behaviour for Macs (and some PCs too).

To minimize the risk of something like this happening when using the stock RAM in combination with aftermarket RAM, the timings should be matched exactly.

tl;dr

Yes you are right that in some combinations of mismatched RAM, the Mac won't boot in any configuration. However, what is also true is that with other combinations of mismatched RAM, sometimes the machine will boot but only in very specific RAM configurations. One should not be surprised by this, because it happens.

I have confirmed by both benchmark results and CPUZ in BootCamp Windows that with both the stock RAM and the Ballistix installed together all modules run at CL17.

No surprise there either. If you tested JVNeurmann's machine the same way, it would likely be CL17 too... in the specific configuration that actually works.

 

[SaSaSushi]

The bolded statement is not necessarily accurate. This is actually the specific issue I'm talking about, and it sometimes happens with Macs. Mismatched memory doesn't boot. Change the configuration, and then it boots. Change it back, and it doesn't boot. However, it depends on the specific machine, and it depends on the specific specs of the memory purchased.

Well, with all due respect, "Sometimes happens with Mac" isn't a very scientific explanation.

The specific machine in this case is the 2017 iMac and the specific memory is Crucial Ballistix Sport LT, both identical in both of our machines. The memory is not mismatched. All four modules are 260-pin SO-DIMM PC4-2400. How does sometimes happen explain the fact that the RAM is working for JVNeumann with Apple in DIMM1 and Ballistix in DIMM0? What is your scientific explanation for the fact that there are several other users in these forums using the Ballistix in combination with the stock RAM with exact same machine with no problems?

I wouldn't be the least bit surprised if, following the instructions in my previous reply, JVNeumann was able to boot his machine in the other configuration with no problems at all.
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No surprise there either. If you tested JVNeurmann's machine the same way, it would likely be CL17 too... in the specific configuration that actually works.

The CAS latency is not determined by where the slowest part is installed in the machine. This is what is configured during the 30-second to one minute black screen at first boot after RAM configuration changes. In both configurations with Apple and Ballistix I confirmed CL17 and CL16 with Ballistix alone.

 

[EugW]

Well, with all due respect, "Sometimes happens with Mac" isn't a very scientific explanation.

The specific machine in this case is the 2017 iMac and the specific memory is Crucial Ballistix Sport LT, both identical in both of our machines. The memory is not mismatched. All four modules are 260-pin SO-DIMM PC4-2400. How does sometimes happen explain the fact that the RAM is working for JVNeumann with Apple in DIMM1 and Ballistix in DIMM0? What is your scientific explanation for the fact that there are several other users in these forums using the Ballistix in combination with the stock RAM with no problems?

I wouldn't be the least bit surprised if, following the instructions in my previous reply, JVNeumann was able to boot his machine in the other configuration with no problems at all.

The guy said he tried it a bazillion times already. It only works in a specific configuration. Basically you're saying you're right and he's wrong, whereas I'm saying you both could be right, because this is a known issue with previous Macs, so it shouldn't come as a surprise that it could also happen for the 2017.

BTW, it should also be noted that even with exactly matched timings, sometimes a machine will not boot with aftermarket RAM. This situation doesn't seem to happen often, but it does happen too.

Finally, there is another situation which has also occurred with Macs, but this was a long time ago and doesn't apply to current Intel Macs AFAIK. In older machines if you put faster aftermarket RAM in the machine along with slower stock RAM, in a certain configuration the machine would actually try to run ALL the RAM at the faster speed, essentially overclocking the stock RAM. Interestingly, if you changed the configuration on these old Macs then it would run ALL the RAM at the slower speed.

 

[SaSaSushi]

The guy said he tried it a bazillion times already. It only works in a specific configuration. Basically you're saying you're right and he's wrong, whereas I'm saying you both could be right, because this is a known issue with previous Macs, so it shouldn't come as a surprise that it could also happen for the 2017.

He said he tried it a bazillion times with Apple stock RAM in DIMM0 and Ballistix in DIMM1 but that it worked just fine the other way. I'm saying if it were a mismatched RAM with different timings matter it wouldn't boot in either configuration.

I think he should also try a PRAM and SMC reset.

 

[themediadude]

So it looks like I can just use my Apple stock RAM along with my OWC RAM and it does not matter if I have the stock RAM in the primary slots.

 

[JVNeumann]

Are you boys fighting over me?

Anyway, seeing as I already bought the RAM like 2 months ago, I just need to figure out my best path forward. So in my current configuration, with Apple stock RAM in DIMM1, can someone explain to me exactly what I'm losing compared to having it back in its native DIMM0?

 

[EugW]

Are you boys fighting over me?

Anyway, seeing as I already bought the RAM like 2 months ago, I just need to figure out my best path forward. So in my current configuration, with Apple stock RAM in DIMM1, can someone explain to me exactly what I'm losing compared to having it back in its native DIMM0?

Nothing. If it works and assuming you’re running at cl17 then it should be fine. AFAIK you can’t confirm the cl17 speed in OS X though.

My point is though if you’re buying now and don’t know what to get, getting RAM with the wrong timings can cause weird issues like you experienced. To minimize compatibility issues, one should buy ram with the exact same timings. Much less risk of encountering what you encountered.

However. If you are going to discard the original stock ram then this doesn’t matter.

 

[SaSaSushi]

Anyway, seeing as I already bought the RAM like 2 months ago, I just need to figure out my best path forward. So in my current configuration, with Apple stock RAM in DIMM1, can someone explain to me exactly what I'm losing compared to having it back in its native DIMM0?

You lose nothing. Just use it that way until, and if, you upgrade to 64GB of Ballistix.
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So it looks like I can just use my Apple stock RAM along with my OWC RAM and it does not matter if I have the stock RAM in the primary slots.

You can keep the Apple stock RAM in place along with your OWC RAM if you like. So long as it is PC4-2400 it should work with no problems at all even if it has a different CAS Latency (CL). In that event the iMac will simply run all of the installed RAM at the speed of the lowest (in this case highest CL) modules. It doesn't matter which slots it is installed in.

If you mix together RAM of different transfer rates and/or use lower quality parts you can run into problems on a Mac.

 

[nambuccaheadsau]

Enough! Giving us a headache.

 

[SaSaSushi]

By the way, I recommend the following as examples of quality RAM, Crucial, Samsung, Hynix, Micron (Crucial is the consumer division) and Toshiba among others.

 

[themediadude]

Thanks all! Everything works!