Adding more memory to a Mac Pro (1 Viewer)

[Ronald Epstein]

Okay guys, down to the wire here and I could really use your
help as I did buy memory, it is due tomorrow, but with a different
configuration.

Let me take you step-by-step.

Through CRUCIAL MEMORY I downloaded a memory scanner for my
Mac Pro (4 core) and got this information about my system:

This is the current memory configuration.

I talked with a Crucial Memory agent this morning who recommended
this upgrade....

Notice how instead of 512MB memory (as in the original configuration)
the company is recommending 2x2GB modules.

I went ahead and ordered these as Crucial does have a guarantee
that it will work or money back.

So now, the question I need from all of you is, will it work?

Also, can someone give me a very easy explanation on where to
exactly place the new 2x2GB chips in the Mac?

I take it that it should go on the second riser below the original
configuration on the first riser? I have yet to even open my Mac Pro
so I have no idea what any of this looks like.

Perhaps the diagram on the first photo above will help someone
to explain this to me.

 

[Ken Chan]

In this case, I would order one more pair of 2GB each (4 GB more, giving you 8GB total). Then install like this:

A: 2GB 2GB
B: 2GB 2GB

Sell the old ones. Same manufacturer, in a quad-channel configuration. No lingering doubts about whether this is an optimal setup.

 

[Ronald Epstein]

Ken,

Is this absolutely necessary?

Are you saying I can't just add the memory I ordered to
the queue?

What will happen if I mix and match?

I mean, I just spent nearly $200 for this memory and I am
not so certain I can sell (nor spend the time trying) the other memory.
You are suggesting I spend another $200 just to get an exact match?!

Why is Crucial so certain that with my current setup that
the memory they are sending me, though not an exact match, won't work?

Please explain further. Appreciate it.

 

[DavidJ]

It is my understanding that it will work. You just won't be operating at maximum efficiency and how crucial that is depends on the use and is open to debate.

I'm sure some others who have contributed to the thread can give you a more exact answer, but without looking it up this is what I recall.

 

[Ronald Epstein]

I called Crucial, and essentially they said "not a problem."

The most important aspect is that the ram speed matches. I need
to check that ALL ram is either 667mhz or 800mhz across the board
and PC2 5300 or PC2 6400 across the board.

I don't quite understand this continued talk of "optimized performance."

I am upping my ram by 4 GB. How much performance am I going
to suffer? I mean, this is a MAJOR amount of ram upgrade. Even if
I got 3GB extra performance from the added 4GB do you really think
I would notice the difference?

I am only looking for a marginal bump in bootup speed and
needed memory bandwidth so having all these startups and programs
running at the same time isn't slowing down my performance.

Once again, if anyone is still disputing the fact I am mixing and
matching my memory, please speak up.

Thanks for all the advice.

 

[DavidJ]

Putting that much additional ram into your machine should give you a big boost. Having four identical matching sticks would give you a tiny, essentially imperceptible boost because it would be quad channel. See Ken's link above where they benchmarked the quad channel configuration vs a dual configuration. Basically, I'd say don't worry about it. Things should run much better for you right off the bat and you can always add another pair of 2 gig sticks later should you decide you need it (but even here the overriding factor should be needing more ram not just bumping to quad channel).

 

[Ken Chan]

No, it's not absolutely necessary.

To understand the problem, both the amount of RAM you have and the speed of that RAM matter. The amount generally matters much more. If you have six apps that each use 1GB of memory, and you only have 4GB of RAM, then you end up swapping RAM to and from the disk -- that's the Page Out and Page In displayed in the Activity Monitor -- and swapping is slow.

Whenever the program's memory is "in place" in the RAM, then the speed at which it can read and write to that RAM matters. For example, EyeTV has to read an MPEG-2 frame of a TV show to decompress it and throw it on the screen, 30 times per second. The faster it can do that, the less chance of stutter and the more time it leaves for everything else you are running simultaneously. The measure here is bandwidth, as opposed to capacity. Now the EyeTV example is nowhere near being limited by the bandwidth, but there are a few things that are. And for those operations, if you don't have the bandwidth, then no amount of extra capacity matters.

Off the bat, I can't think of any "normal" things that are constrained by memory bandwidth. Examples for other kinds of bandwidth that do come into play: processor power can easily determine whether you can play HD content; disk transfer rate and whether you have a RAID or not matters for working with (uncompressed) HD; your internet connection regulates streaming.

So if memory bandwidth is not a limiting factor that determines that some things won't work, then the speed of your memory only means that some things run faster. Only some things, because the bottlenecks in the other cases are elsewhere.

In the benchmarks I posted earlier, the performance benefit for using quad-channel was: usually nothing, but about 15% faster in a few cases. Maybe a coincidence, but here are some benchmarks that show that if you fill all eight slots the memory runs about 15% faster. (That was for a later model Mac Pro than yours, though.)

So bottom line: you've spent good money on this system, and you're spending a little more, and there are simple steps you can take that don't make the system run slower, but might actually make it run faster.

Could you tell the difference with the things that you do? I have no idea. But here is where it sorta matters whether you're a glass half-full or half-empty kind of guy. For me, there's very clearly a "right way" to do it, and it's pretty straightforward, and I never wonder if I'm "throwing away" "free performance" because I didn't do it that way. (Of course, the memory sticks themselves aren't free, but....) On the other hand, you might say, hey it works, and even if doing it another way might be marginally faster, it's not a limiting factor in my life, so I'm not going to worry about it. Both perspectives are reasonable.

If this is confusing instead of helpful, I will stop

 

[Ronald Epstein]

Ken,

This is helpful and please don't take my frustrations over all this
personally. I am very grateful for your help.

This is all new to me, and basically this is what Crucial recommended.

I'm not going to spend $400 on memory. As David pointed out, even
if the ram is not fully optimized, I should see a big performance boost
with the memory upgrade and it should solve the current bottlenecking
problems I am experiencing.

Just have to hope I can figure out how to add the memory.

 

[Carlo_M]

On a separate tangent, I find that my Macbook Pro (4GB of RAM) sometimes slows down in bootup speed over the course of months due to a lot of OSX updates (i.e. 10.5.2 -> 10.5.3 -> 10.5.4). What I do is defragment the drive and that has always reduced my bootup time. I don't use a fancy defragging tool. I use the free demo version of iDefrag to see how fragmented the drive is (the free version allows you to do this but not actually defrag the drive). Then I use Carbon Copy Cloner (also free) to clone my drive to an external firewire hard drive (make sure the external hard drive's firewire chipset is compatible with OSX to be able to boot from it, not all firewire chipsets are bootable). Then I boot my MBP from the external drive and clone back to the internal hard drive. Takes about an hour and a half each way, and then when I run iDefrag nearly all of the files are contiguous. And the way CCC copies files it copies the system and program files first then your personal files last, which in a way "optimizes" the data layout in your HD, in addition to defragging.

I do this about every 6-9 months. This is a low cost solution (assuming you already have the external HD, and even if you don't they are fairly cheap nowadays) in comparison to always adding RAM or a larger HD.

 

[Ronald Epstein]

Well, memory is added.

I must give a huge amount of kudos to Crucial Memory. Not only
did I get a great price on memory shipped overnight, but their tech
support walked me through the entire process of installing memory.
They were exceptionally patient and polite.

Basically, since my original 3GB configuration (2x1GB and 2x512)
was evenly spread out between RISER A and B, I added the two new
DIMM modules to slots 3 and 4 on RISER A. The computer immediately
identified that I had 7 Gigs of Ram.

See that second image in Post #5 above of the Activity Monitor?
With the same programs open I went from 685.17 Free Memory to
5.52GB. WOW!

Thank you all for your patience and help.

 

[Ronald Epstein]

Well, this was accurately predicted.

After upgrading the memory I found out that I am still getting
occasional "spinning beach ball" lockups on my Mac Pro.

It does seem as if there is some incompatibility happening between
software but it would take forever for me to figure out which programs
they are.