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Adding different ram size in MacPro (5,1) 2.8 quad core?

R

Randall Flagg

macrumors newbie
Original poster
Jan 13, 2011
11
0
Canada
Hi,

Everyone said that MacPro 5,1 isn't dual channel or tripple, that you can put different ram size in it...

It is true? It seem that many people do that...

Crucial: They sell only Dual kit ? (http://goo.gl/vNYwG)

Kingston (http://goo.gl/eTSvy):
This system supports triple channel mode when three identical modules are installed. Kingston offers K3 kits to optimize performance and K4 kits to achieve maximum configurations.

This system supports DDR3 1066MHz (KTA-MP1066) and 1333MHz (KTA-MP1333) memory depending on processor model
Click to expand...

I have the 2.8Ghz quad core with 3x2GB ram pc-8500 in it. So how can i upgrade this, and have maximum performance ?

My first idea was to add a 4GB in it like the KTA-MP1333/4G from Kingston 1333mhz ECC module.

What is the downside and the upside of it ?
 
As the guide says, when you install RAM, if you want maximum performance, install it in sets of 3 identical chips. You can have two different sets of three chips.

I'm not sure if the Mac Pro 5,1s support install just a single RAM chip by itself. I know the 2008 Mac Pros would certainly not let you do that. I know the 5,1's at least support pairs, and honestly, it would be better to do 2x2 gig chips to at least do dual channel.
 
goMac said:
As the guide says, when you install RAM, if you want maximum performance, install it in sets of 3 identical chips. You can have two different sets of three chips.

I'm not sure if the Mac Pro 5,1s support install just a single RAM chip by itself. I know the 2008 Mac Pros would certainly not let you do that. I know the 5,1's at least support pairs, and honestly, it would be better to do 2x2 gig chips to at least do dual channel.
Click to expand...

I don't think you can do tripple or dual channel, it's one or the other. I am not even sure that the MP do dual or tripple, since the speed don't change at all?

What will happen if i put a 4GB in it ? slow perf ? I hear that you have to put it in slot #2 to make it work...that's weird: http://discussions.apple.com/message.jspa?messageID=12215163#12215163

This is all pretty unclear.
 
'09 and '10 Mac Pros support dual and triple channel. they do not need to be installed in pairs, I don't think any Mac has needed that since the PowerMac G5.

the performance benefit from dual or triple channel is hardly worth thinking about. get however much you need in the largest DIMM capacity you can afford.
 
Okay so there is no problem installing one 4G to go along with the 3x2G i have? nice.

1333mhz or 1066mhz should i choose? If i want to upgrade the processor some day, should i take 1333mhz instead ?
 
Last edited:
Wether or not you think it works well doesn't mean it's working as well as it should or could be.

For example in a 2010 MP I read that 12GB (4x3) over 3 channels is faster than 16GB (8x2) over 2 Channels. I would have thought the 16GB would be faster...

I couldn't say for sure but it may slow things down, even when you think it should theoretically speed things up.

From every source I've read matched triple channel is best
 
philipma1957 said:
buy this

http://www.superbiiz.com/detail.php...333-12GB-3x-4GB-ECC-Triple-Channel-Memory-Kit

use discount code Hibernate10 for ten bucks off price is 143 minus 10 bucks 133 for 12 gb! hold on to the 6gb for a while(a month or so) then sell on ebay!
Click to expand...

Since i am in canada, this deal doesn't apply to me, but thanks for sharing, maybe another can benefit from it :)

DeeEss said:
Wether or not you think it works well doesn't mean it's working as well as it should or could be.

For example in a 2010 MP I read that 12GB (4x3) over 3 channels is faster than 16GB (8x2) over 2 Channels. I would have thought the 16GB would be faster...

I couldn't say for sure but it may slow things down, even when you think it should theoretically speed things up.

From every source I've read matched triple channel is best
Click to expand...

Yeah i'll stick with 3 channels then, because if i add another 4GB, it will ask me to put it in slot #2, and i think that will break the Tripple channel because i'll have 2GB stick in #1,#3 and #4, and i think you have to put all stick all together to benefit the tripple channel? or it will detect 3 identical dimm anyway ? hey that's a good question :)

But the question about the Mhz remain unanswered :)

Can i buy 1333mhz without problem ? Like the KTA-MP1333/4G from Kingston for instance. I know that i will run at 1066mhz anyway, i just want to be ready if i upgrade the processor in 2-3 years and keep the same ram.
 
Randall Flagg said:
Since i am in canada, this deal doesn't apply to me, but thanks for sharing, maybe another can benefit from it :)



Yeah i'll stick with 3 channels then, because if i add another 4GB, it will ask me to put it in slot #2, and i think that will break the Tripple channel because i'll have 2GB stick in #1,#3 and #4, and i think you have to put all stick all together to benefit the tripple channel? or it will detect 3 identical dimm anyway ? hey that's a good question :)

But the question about the Mhz remain unanswered :)

Can i buy 1333mhz without problem ? Like the KTA-MP1333/4G from Kingston for instance. I know that i will run at 1066mhz anyway, i just want to be ready if i upgrade the processor in 2-3 years and keep the same ram.
Click to expand...

yes it is auto down clock 1333 to 1066
 
DeeEss said:
Wether or not you think it works well doesn't mean it's working as well as it should or could be.

For example in a 2010 MP I read that 12GB (4x3) over 3 channels is faster than 16GB (8x2) over 2 Channels. I would have thought the 16GB would be faster...

I couldn't say for sure but it may slow things down, even when you think it should theoretically speed things up.

From every source I've read matched triple channel is best
Click to expand...

More GB of ram does not make the ram faster. It just gives you a bigger threshold before you will have to swap to disk. The triple channel design gives a very small speed boost. However, as long as you use the extra ram, filling 4 slots will give you better performance than filling 3 slots and having to swap to disk.
 
DeeEss said:
For example in a 2010 MP I read that 12GB (4x3) over 3 channels is faster than 16GB (8x2) over 2 Channels. I would have thought the 16GB would be faster...
Click to expand...

If you exceed 12GB of memory usage, the 16GB should be massively faster than 12GB of RAM + hard drive swap. Unless of course you also exceed the 16GB and you're hard drive swapping anyway, albeit to a lesser degree.
 
I've tired to gather a full understanding of whether or not pairing your ram, but having different sizes is a good or a bad thing.

For years I've had this setup (pic below). I want to add 8GB's more, but wasn't sure if I should change all the ram to be the same GB size per stick.

Can anyone comment on this please?



Thank you


ScreenShot2013-01-25at115405AM.png
 
Keep in mind that Mac Pros are based on a server architecture, where optimizing performance is a core design element. The Nehalem/Westmere architectures were on the one hand, very complex wrt memory and on the other, very accommodating albeit with a performance penalty. The architecture and chipsets were designed (for the most part) for triple channel memory, and banks of three provided best performance. That said, Apple offered these systems with either 4 or 8 memory slots. Maximum performance came from using 3 slots. You could use 4 (my factory BTO was 4x2GB) but performance was not optimized. Note that by "performance" I mean memory performance, one factor in overall workload throughput. I have done work for a major server manufacturer, and their estimate was that performance implications were usually less than 5%. If you have 100 servers running at 80% utilization, this matters. But most people don't. Most people are more likely to see a dramatic performance hit if VM is required; therefore, would rather have more memory rather than configurations with optimized memory performance.
 
Well, I don't do anything crazy with my Mac. I mostly just run like 10 tabs in Google Chrome, Parallels (while dedicating 2GB VM . 1.5GB RM) and run Safari and a few other small chatting programs on various monitors.

I've been noticing a lot of my ram gets sucked up after I use a browser for a while. It's a good thing I downloaded an automatic memory cleaner. Looking right now, I only have 3.43 GB free and I'm just doing the "usual" for myself.

You think I can add the 2 4GB chips and I'll be set?
 
marker227 said:
I only have 3.43 GB free and I'm just doing the "usual" for myself.

You think I can add the 2 4GB chips and I'll be set?
Click to expand...

You can, but question is: do you really need it? Free = unused = waste (in general). If your normal usage never exceeds these ~6.5GB, adding more won't make a difference. Check this out an determine if you really need more RAM: http://support.apple.com/kb/HT1342
BTW, memory cleaners were good for Win 98 ;) OSes moved forward in memory management area since then.
 
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