MP 1,1-5,1 RAM memory downspeed in Mac pro 2009

[thefbi]

Hello,
i have restored a Mac pro 2009. Flashed in 5.1.
All is fine, but i have a problem for the RAM. I have 4 RAM slots. I have buy RAM on Ebay : https://www.ebay.com/itm/64GB-4x16G...5-1/303061386911?_trksid=p2485497.m4902.l9144

When i put the 4 16Gb in my 4 slots, my RAM is at 800 Mhz. If i put only 3 RAM, i have 1066 Mhz. YOu have an idea why i cant have 4 at 1066 Mhz.

I am a newbie and my knowledge in all of this is limited...

 

[tommy chen]

a macpro needs 2R4 and yours are 4R4

 

[thefbi]

Thank you. I have found a post here : https://forum.macbidouille.com/index.php?s=&showtopic=380572&view=findpost&p=4022527

That say that the Mac pro i have support max 3 x 16Gb of RAM. Because, you say i have not the right RAM, but as you can see in my screenshots, with 3x16, it is OK...

 

[Macschrauber]

and, 2nd, those are 1066 Ram anyway.

Live with it, speed difference is not really noticeable.

 

[thefbi]

OK, thank you.
So, it is better to have 3x16 @ 1066 than 4x16 @ 800 i thing ?

 

[Macschrauber]

Depends on what you do, in theory yes, but when memory pressure is high 4x16 is better.

Do your work and watch memory pressure with Activity Monitor.

 

[thefbi]

OK, thank you

 

[minifridge1138]

You can have 4x16GB and 1066 MHz.
If your RAM is slowing down to 800 MHz, then you’re using the wrong ram. There’s more to RAM than just capacity.
Buy the right ones and you’ll see the correct speed.

 

[MarkC426]

I thought max supported on a single processor Mac was 48gb (3x16) anyway.

 

[minifridge1138]

Oh, missed that it was a single processor. Yes, I think 48GB is the max. So I’d stick with the 3x16GB.

 

[thefbi]

OK, thank you. And if in a futur i want to upgrade this to a double proc, is it "easely" possible by replace the tray, with another tray with double CPU like this one : https://www.ricardo.ch/fr/a/cpu-board-tray-apple-mac-pro-4-1-dual!-1102726740/
Or not ?

 

[kohlson]

Take a look at some of the sticky threads at the top of the this forum. Specifically, the CPU sticky. If you need more RAM - up to 64GB - you can do this with an X-series processor. An example is the X5680, readily available on eBay. It will also provide six cores of 3.33 MHz.

The "newer generation" CPUs - newer than the one you started with - also enable the faster RAM speed you're looking for.

Going to a dual processor tray can be done, but read up on that. Of note is that all 4,1 cMPs (even those flashed to 5,1) use delidded CPUs. This is a little more challenging.

 

[thefbi]

Yes, i have already replace my processor by a X5690 at 3.46 MHz.
So you think all four RAM clips should work ?

If yes, i have found this one, wich is 2R4 like InioX said. See screenshot (I didn't buy it).

So i dont know if it is a RAM problem or a Hardware limitation, even with the X5690 processor...

 

[thefbi]

Any idea ??

 

[Macschrauber]

I had used ram with this spec with a single x5680 and got 64GB / 1333 and Mojave, Firmware 144.0.0.0

 

[thefbi]

OK thank you. If i buy it, i will come back to post results. Actually, with 48Go, and with my work (even with Photoshop, Premiere, Audition), it is OK. So i will think about buy or not again RAM...

 

[Macschrauber]

With 4 memory sticks you will not have triple channel no more. This will give less nemory bandwith.

Anyway, with high memory pressure more ram is better. If you have no memory pressure go with 3 sticks in triple channel.

More is not better in every use case...

 

[thefbi]

OK, thank you

 

[Snow Tiger]

With a X5690 Xeon installed in your single processor cMP , you should have no problem installing 64 GB (4 x 16 GB ) DDR3 1333 MHz ECC memory for the highest capacity possible .

Recommended installation for highest performance is 48 GB ( 3 x 16 GB ) , to activate tri channel memory optimization ( a feature in this Xeon ) . Your System will be around 10-12 percent faster compared to alternative configurations .

System boot ROM version should be 144.0.0.0.0 .

You should not use either Quad Rank or 32GB modules in these Macs .

Here is a list of known good 1333 MHz modules for your Mac :

16GB = Samsung M393B2G70AH0-YH9 .

16GB = Samsung M393B2G70BH0-YH9 (low voltage) .

16GB = Micron MT36KSF2G72PZ-1G4 ( low voltage ) .

16GB = Samsung M393B2G70BH0-YK0 (1600 MHz) . Downscales to 1333 MHz .

16GB = Nanya NT16GC72C4NB0NL-CG ( low voltage ) .

The prices of 16 GB modules is inching upwards lately ...

 

[thefbi]

OK, thank you very much for these explanations