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pastrychef's Asus ROG Strix Z370-G Gaming (WI-FI AC) build w/ i9-9900K + AMD 6600 XT

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Hey there. I have a similar system, but with a z370 E board. It is rock solid with 2x16 GB installed in (numbered from the CPU) slots 0 and 2. If I install things in 1, 3 it will not boot. I have seen others mention this as well.

However, if I install memory in all four slots, it will boot, but will eventually crash. The crash seems to be memory related, such as when it tries to actually touch that RAM.

I did increase the number of slots from 2 to 4 in the config, and I did hard-code the memory sticks in a manner similar to what you did. Without doing this, it would not find the additional memory. I have not tried just increasing the slot count without hard-coding the RAM.

In System Information, it finds the two sticks I currently have installed, and correctly identifies them as Corsair and the correct part number, and the correct speed (which doesn't match the package, but does match what the BIOS claims they are... strange!)

Do you have any suggestions on what I could to do make those other two slots work properly?
 

pastrychef

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Joined
May 29, 2013
Messages
18,362
Motherboard
Asus Z370-G Gaming (Wi-Fi AC)
CPU
i9-9900K OC'd @ 5.0GHz
Graphics
RX 6600 XT
Mac
  1. MacBook
  2. Mac Pro
Classic Mac
  1. iBook
  2. Power Mac
  3. PowerBook
Mobile Phone
  1. iOS
Hey there. I have a similar system, but with a z370 E board. It is rock solid with 2x16 GB installed in (numbered from the CPU) slots 0 and 2. If I install things in 1, 3 it will not boot. I have seen others mention this as well.

However, if I install memory in all four slots, it will boot, but will eventually crash. The crash seems to be memory related, such as when it tries to actually touch that RAM.

I did increase the number of slots from 2 to 4 in the config, and I did hard-code the memory sticks in a manner similar to what you did. Without doing this, it would not find the additional memory. I have not tried just increasing the slot count without hard-coding the RAM.

In System Information, it finds the two sticks I currently have installed, and correctly identifies them as Corsair and the correct part number, and the correct speed (which doesn't match the package, but does match what the BIOS claims they are... strange!)

Do you have any suggestions on what I could to do make those other two slots work properly?

The only thing I have done is manually add in the RAM in to config.plist. As far as I can tell, macOS and apps now see and use all of the memory and the system has been rock solid. I have gone over 6 days of uptime before I had to restart.

Have you checked for BIOS updates? I updated the BIOS a little over a week ago and it seemed to help with stability with my overclocks. Since I updated, I have not had a single freeze/crash/panic.

Do you have XMP enabled in BIOS? Have you tried without XMP and RAM speeds set to something like 2400MHz or 2666MHz? Do you have XMP enabled in your config.plist (Boot section in Clover Configurator)? Is your CPU overclocked?
 
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Thanks for the quick reply!

I'm currently not overclocking in any way; I want to get a system that I believe is stable as a baseline before I start fiddling around in unknown territory.

In the BIOS, XMP is disabled, and each of the 4 sticks comes up as 2133 Mhz, and the CPU as 3.7 Ghz. I assume this means I'm not pushing any limits; I'm rather new to modern PCs, having been more of a software guy for the last 10 years. I think the last PC build I did was about that long ago.

I have upgraded my BIOS to 0605, which seems to be the latest.

(update) I also verified in clover, I have "XMPDetection" set to "no"
 
Last edited:

pastrychef

Moderator
Joined
May 29, 2013
Messages
18,362
Motherboard
Asus Z370-G Gaming (Wi-Fi AC)
CPU
i9-9900K OC'd @ 5.0GHz
Graphics
RX 6600 XT
Mac
  1. MacBook
  2. Mac Pro
Classic Mac
  1. iBook
  2. Power Mac
  3. PowerBook
Mobile Phone
  1. iOS
Thanks for the quick reply!

I'm currently not overclocking in any way; I want to get a system that I believe is stable as a baseline before I start fiddling around in unknown territory.

In the BIOS, XMP is disabled, and each of the 4 sticks comes up as 2133 Mhz, and the CPU as 3.7 Ghz. I assume this means I'm not pushing any limits; I'm rather new to modern PCs, having been more of a software guy for the last 10 years. I think the last PC build I did was about that long ago.

I have upgraded my BIOS to 0605, which seems to be the latest.

(update) I also verified in clover, I have "XMPDetection" set to "no"

Yes, I also updated to BIOS 0605.

Yes, keeping stock speeds and not overclocking during testing helps to simplify troubleshooting.

I have XMP set to yes in my BIOS and config.plist.

I just tested my system without the manually entered RAM specs in to config.plist and here's what I observed:
  • iStat Menus seemed to recognize that my system has 64GB (4x16GB) of RAM.
  • About this Mac shows 32GB @ 3478MHz which means that at least XMP is working.
  • System Information shows Bank 0 and Bank 1 occupied.
Screen Shot 2017-12-25 at 3.41.13 AM.png Screen Shot 2017-12-25 at 3.41.28 AM.png Screen Shot 2017-12-25 at 3.41.58 AM.png
 
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I can't even get osx to boot with all four sticks inserted. I'm going to run a memtest on the box over night with all four installed to ensure I don't have a hardware issue.

I'd not trust that your system identified 64 GB, since if I define all four sticks and boot, the system claims it has 64 GB, but if I try to use it (say with the homebrew "memtester" trying to allocate 40 GB) it will crash instantly. This also happens if I manage to get it to boot with all 4 sticks inserted and manually entering memory info; it seems to not be properly mapping it into the CPU's MMU in some way.
 
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Update: if I enable XMP in the BIOS and Clover, when the system boots, the RAM is listed as it's max (3000 Mhz) and the part number and manufacturer are correctly read. This is for 2 sticks; I still can't get past a failure to boot with all four installed with or without the memory's configuration in place, although I've not tried with 4 sticks and XMP on.
 

pastrychef

Moderator
Joined
May 29, 2013
Messages
18,362
Motherboard
Asus Z370-G Gaming (Wi-Fi AC)
CPU
i9-9900K OC'd @ 5.0GHz
Graphics
RX 6600 XT
Mac
  1. MacBook
  2. Mac Pro
Classic Mac
  1. iBook
  2. Power Mac
  3. PowerBook
Mobile Phone
  1. iOS
I can't even get osx to boot with all four sticks inserted. I'm going to run a memtest on the box over night with all four installed to ensure I don't have a hardware issue.

I'd not trust that your system identified 64 GB, since if I define all four sticks and boot, the system claims it has 64 GB, but if I try to use it (say with the homebrew "memtester" trying to allocate 40 GB) it will crash instantly. This also happens if I manage to get it to boot with all 4 sticks inserted and manually entering memory info; it seems to not be properly mapping it into the CPU's MMU in some way.

To test if the system actually REALLY sees and uses all 64GB, I set up a 50GB RAM disk as per directions here. Then, I copied a 45GB Blu-ray image to it and I currently have the Blu-ray playing in VLC from the RAM disk as I type this.

Screen Shot 2017-12-25 at 5.03.47 AM.png Screen Shot 2017-12-25 at 5.08.52 AM.png

Btw, this is the first time I've experience memory swapping with 64GB and there's a noticeable lagginess.
 
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A ram disk might work; the Homebrew installed "memtester" also wires the memory, so it cannot cause swapping, and must use actual physical RAM. If it cannot allocate enough (say, you only have 32 and you try to use 30 or so) it will fail to allocate it.

From experience, this is the best method to ensure your memory is really working while running OSX.

I'm beginning to believe either my second set of 16 GB sticks are bad, or the motherboard is bad. I'll purchase an alternate motherboard and see what happens, and try the RAM I have trouble with in the first two slots, and run a memtest on it from an Ubuntu boot USB drive.
 

pastrychef

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May 29, 2013
Messages
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Motherboard
Asus Z370-G Gaming (Wi-Fi AC)
CPU
i9-9900K OC'd @ 5.0GHz
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RX 6600 XT
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If you look at the image above, the RAM disk used all the memory and there was no swapping yet. It wasn't until I started doing other stuff while the Blu-ray was playing that swapping began.
 
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I understand that the ram disk might be a way to test this, but my knowledge of how memory management on Unix-like systems works tells me that wired memory is guaranteed not to be swapped out, and must only reside in physical RAM, and at the specific address it is currently mapped into. The OS itself uses this for buffers it will be sending to hardware to DMA into, for instance. It ensures the memory doesn't get swapped out (which would crash a DMA operation) or whatnot, and it cannot be compressed.

It's a small little tool, easily installed with "brew install memtester", and run like "memtester 50G"
 
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