MP 1,1-5,1 Recommended memory size for a 5,1?

[TECK]

I have a 12 core cMP 2010 with 128GB of RAM. I don't remember where I read on these forums but someone was saying the Mac will be faster with 96GB? I purchased the memory sticks second hand for a ridiculously low price, that is way I decided to get 8 x16GB.

Can you please let me know what is the recommended configuration?

 

[rodedwards]

Apparently 96Gb ram on these is faster than 128Gb ram when your system isn't using more than 96Gb ram. If you find you need more than 96Gb ram then 128Gb is faster. I have 96Gb in mine

 

[Soba]

I have a 12 core cMP 2010 with 128GB of RAM. I don't remember where I read on these forums but someone was saying the Mac will be faster with 96GB? I purchased the memory sticks second hand for a ridiculously low price, that is way I decided to get 8 x16GB.

Can you please let me know what is the recommended configuration?

The 2010 uses a triple channel memory controller, so there is a slight performance boost if you install DIMMs in matched groups of 3. If your work doesn’t require more than 96GB of RAM, remove one DIMM from each bank in your Mac. You might not notice a real-world difference day to day, depending on what you’re doing, but it is there.

If your application will be RAM starved with only 96GB, then keep all 128GB.

What CPUs do you have installed and what is the speed of your RAM?

 

[TECK]

I have installed dual X5690s 3.46Ghz and 8x16GB of Hynix PC3L-10600R DDR3 1333Mhz ECC.

 

[Soba]

I have installed dual X5690s 3.46Ghz and 8x16GB of Hynix PC3L-10600R DDR3 1333Mhz ECC.

That is as fast as it can be! Remove a DIMM from slot 4 and a DIMM from slot 8 and your system will run optimally.

You might have already done this when you installed your X5690, but after you remove the DIMMs (or even if you decide not to remove the DIMMs), clear your NVRAM 3 times in a row by holding Cmd+Opt+P+R when you hear your system's startup chime. This will ensure your RAM is operating at 1333MHz instead of 1066MHz.

 

[h9826790]

I have installed dual X5690s 3.46Ghz and 8x16GB of Hynix PC3L-10600R DDR3 1333Mhz ECC.

Use your cMP with this memory config.

Then in a day of normal work, check your memory usage occasionally. If memory used (including cache) can go above 96GB, then keep the current config.

MacOS usually can use extra memory quite well (as cache) to further speed up the system. If you rarely reboot your system but let it run 24/7 or just use sleep mode, the extra RAM should able to serve you better.

MacOS can keep as much data as possible in the extra RAM. When you need them, the OS no need to load them from the hard drive again, because they are already inside the RAM. This is the idea.

Of course, if you are looking for best benchmarks score, then go for 96GB.

 

[TECK]

clear your NVRAM 3 times in a row by holding Cmd+Opt+P+R when you hear your system's startup chime.

I've held down the Command+R+Option+P on a Mac wired keyboard until the chime sounded 3 times, then let it go. The chime sounded the 4th time and system came up but memory still shows as 1066 MHz DDR3 ECC?

The part number HMT42GR7MFR4A-H9 showing clearly 1333Mhz. I tried again the 3 startup chimes and still no 1333Mhz showing into system?

 

[Soba]

The part number HMT42GR7MFR4A-H9 showing clearly 1333Mhz. I tried again the 3 startup chimes and still no 1333Mhz showing into system?

The DIMM specs look correct, but I might be missing something.

What is the version of your BootROM?

 

[TECK]

I’m on Catalina, 144.0.0.0

 

[TECK]

Wait, this is a Mac I’m rebuilding to its max specs as we speak, as I sold my previous 2009 one. I did not put yet inside the 5690 processors.

 

[Soba]

Wait, this is a Mac I’m rebuilding to its max specs as we speak, as I sold my previous 2009 one. I did not put yet inside the 5690 processors.

That is probably the reason. Check the first post of this thread to find the RAM performance of your current CPU:

https://forums.macrumors.com/threads/mac-pro-cpu-compatibility-list.1954766/