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6 GB not cutting it w/ Nehalem Octad

S

steveoc

macrumors regular
Original poster
Nov 6, 2007
238
2
Adirondacks NY
I like to run a lot of moderately intensive apps simultaneously and have lots of windows opened and I find myself constantly up against the wall for RAM. It's not unusual for me to have 15+ apps running at once.

I am considering 6 x 2GB or 8 x 2 GB. (I'm sure my wife would prefer that I just buy 2 x 1 GB sticks, but I doubt that would make an awful lot of differences for the way I run apps)

Any recommendations? I've read many articles, but my eyes are glazing over.
 
Think about it.

With 16 concurrent threads, assuming you have 15 apps plus the Finder running concurrently, 6GB gives you a whopping 384MB (or less than 0.4 GB) per application.
That's not going to be enough! Depends on your applications, but most these days want more than a few hundred megabytes.
Your Mac Pro will be paging RAM to the extreme.

I'd say 1GB per thread should be a good minimum limit. With 16 threads, that's 16GB, or in your case 8 x 2GB memory sticks.

Anything less is not going to make you happy if you like having lots of apps running concurrently.
Even with 8GB total RAM you'd only have 0.5 GB per application. If you run a lot of small utility apps that might be enough, but even Safari and Mail like to have more than 512MB memory these days...


Just to give you an idea if you were to do 3D rendering, the minimum would be 2GB per render thread, preferably 4. (But 8GB memory sticks aren't available yet.)
IMHO the Mac Pro really should have had 6 or 8 RAM slots per CPU, not just 4...

For an octo-core machine 6GB RAM as base configuration is pretty lame and rather useless. It's enough for one or two applications running, but if you never run more than two apps why get an octo-core Nehalem machine? A quad-core would be enough.
12GB should the the bare minimum IMHO.
But in your case I'd recommend 16GB as you like to have lots of applications running.
 
Ok. You can't just divide 6GB by 15. That is now how the system manages ram at all. Furthermore, 6GB / 15 = 400MB, not KB.

OP: You need to check your activity monitor, and see how much it is paging out and if its swapping. You should able to actually make a fairly good guess at how much ram by looking at how much is reserved for each of your monster apps.
 
Oops, sorry about the KB -> MB mistake. Still early morning here and hadn't had my coffee...
Fixed it in original post.

But the point is unchanged, with apps having merely a few hundred MB available that's not going to make them happy.


The OP mentioned there are '15+ apps running at once', which may or may not mean these actually do something.
If they are merely suspended the OS can page that application out almost completely to HD and it doesn't really need any RAM.
But if they are actively crunching numbers then the app will need RAM.
It depends on how many apps are actually doing something.
 
steveoc said:
I like to run a lot of moderately intensive apps simultaneously and have lots of windows opened and I find myself constantly up against the wall for RAM. It's not unusual for me to have 15+ apps running at once.

I am considering 6 x 2GB or 8 x 2 GB. (I'm sure my wife would prefer that I just buy 2 x 1 GB sticks, but I doubt that would make an awful lot of differences for the way I run apps)

Any recommendations? I've read many articles, but my eyes are glazing over.
Click to expand...

Don't worry about the wife. Tell her to stay in the kitchen :p (don't tell my wife I said that :) ) No, seriously now. Buy as much as you can afford. Running all that stuff at once you won't be sorry. I run 10 gigs and wouldn't want any less...
 
If you are looking at activity monitor and looking at just colorful RAM usage pie, then you are likely worrying yourself over nothing.

Likely 6GB is adequate, unless you are acting like monkey on meth with the remote control, and constantly flipping between apps.

If you get a spinning ball within the app, then you are at the RAM limit.

If you get a 1-2 second spinning ball when you switch apps, and no slowdowns within -- it is just the OS making room for the current app in memory. at this point you still have more than enough memory.

You can spend $1k's on memory to save yourself 1-30 seconds a day. Or spend the money on your wife...
 
Dreamail said:
But the point is unchanged, with apps having merely a few hundred MB available that's not going to make them happy.
Click to expand...

zmttoxics is right, you do not divide 6GB by 15 and think that`s whats available to each app. Take a screenshot of Activity Monitor and post it here. There`s plenty of smart people to tell you what to do when we know what Apps you are actually running and which is paging the most.
 
Go for the 8 x 2 gb, you won't regret it. Everything runs very well. I use the CS4 suite and VMware with Win 2003 Server with 4gb dedicated to it. Very nice.
 
I agree. Unless you're trying to tune it for speed in mission critical fashion go for the 8x2GB. And i also agree that Apple gypped us on the RAM slots. The intel reference designs allow for 144GB of RAM in 18x8GB or 72GB in 18x4GB or 36GB in 18x2GB - notice also that 18 is a multiple of 3 and not 4. Jeezzz! Why is it that almost every aspect of the 2009 systems seem to piss me off? It's not just me... I don't feel that way at all about the 2006,~ 2008 systems.

Apple! Dang you! Hehehehe ;)
 
I don't feel the need for more RAM because of what the Activity Monitor indicates. I check the activity monitor when my performance diminishes. It is clear that the bottleneck is memory--it certainly isn't processor power. I quit apps to improve performance when I'd rather leave them running.

I work across several applications in most of what I do whether it is web site work, research, or making multimedia presentations for my students. I switch apps frequently (I'll admit to an ADD tendency that drives me to change activities often). In making a social studies slideshow, I typically work with:

  • Keynote 1-2 GB files
  • Pages
  • Photoshop for masking
  • Graphic Converter for dealing w/ massive arcane file types at the Library of Congress site
  • Circus Ponies Notebook (that little app can suck up ram!)
  • Large NovaMind Files
  • Safari (for easier drag and drop grabs of video)
  • Firefox (for Zotero citation management)
  • QuickTime Pro
  • Google Earth
  • iMovie 09
  • Timeline 3D

Throw in Mail, iTunes, iCal, some OCR, a few utilities, and whatever else I happen to be running and I see the spinning ball much more often than I care to. I don't run VMware as much as I'd like because of the drain on memory.

A $200-300 memory upgrade is not a big expense in terms of a MacPro as long it is "adequate" for quite awhile (Like until 4 GB sticks are cheaper than the current price of 2 GB sticks).

12 GB might have been enough, but for the extra $70 I decided to go with 8 X 2 GB so that I have matching RAM rather than filling the last two slots with unmatched memory later.

As far as feeling cheated by the number of slots--I wholeheartedly agree. I bought the octad rather than the quad largely because it had twice the RAM slots. A MacPro with only 4 slots is inexcusable and 8 slots shouldn't be the top end. I suspect memory will become the limiting factor before processing power.

My G4 came with 64 MB, expandable to 2 GB (Yes--it still runs fine after 10+ yrs). My G5 came with 1 GB and is expandable to 16 GB. The MacPro came with 6 GB and is upgradable to 32 GB.

At base configuration the G4 came with one of four slots filled, and the G5 2 of 8. On my Nehalem Octad 6 of 8 are filled. Furthermore, with the G4 matched pairs were not an issue. On the G4 I filled empty slots one by one, then swapped out the oldest once I ran out of space. Replacing a 64 MB chip with 512 MB is one thing, but dumping a 1 GB stick for a 2 GB stick is another.

Thanks to all for your thoughtful input!
 
Tesselator said:
I agree. Unless you're trying to tune it for speed in mission critical fashion go for the 8x2GB. And i also agree that Apple gypped us on the RAM slots. The intel reference designs allow for 144GB of RAM in 18x8GB or 72GB in 18x4GB or 36GB in 18x2GB - notice also that 18 is a multiple of 3 and not 4. Jeezzz! Why is it that almost every aspect of the 2009 systems seem to piss me off? It's not just me... I don't feel that way at all about the 2006,~ 2008 systems.

Apple! Dang you! Hehehehe ;)
Click to expand...

I can sorta understand the lack of slots on the Octo's... the CPU card just doesn't have much real-estate to work with... and 8 slots does give you 16GB capacity with cheap 2GB DIMMS. However, 4 slots on the quad is unforgivable given all the added real-estate they had to work with... It's bizarre. They could have easily rearranged the layout to accommodate 6 slots on the quad. :confused:
 
Yeah, but the simple answer to that is: They should have added realestate. :D Pretty simple to me. Of course, I'm a simple kinda' guy. ;)
 
steveoc said:
I don't feel the need for more RAM because of what the Activity Monitor indicates. I check the activity monitor when my performance diminishes. It is clear that the bottleneck is memory--it certainly isn't processor power. I quit apps to improve performance when I'd rather leave them running.
Click to expand...

Memory is not the bottleneck, it's a finite resource that you've used up.
At that point (actually, before then in most cases), memory is paged to disk, which is the real bottleneck.

A healthy system is one which pre-emptively pages non-active data to disk, which means that when an app needs more memory, it can simply flush parts that are already on-disk (takes a few milliseconds).

Now, it's true that you could get more memory, but at this point you're likely to see a bigger performance boost per buck by getting better local storage.

If you have 15 apps open, and all of them are paging to disk, they'll be doing 5-6MB/sec each writing to the swap. Of course, the app your currently using that just requested more memory is fairly likely to be reading from the disk at the same time the writes are going on.. :)

The old adage of "no such thing as enough memory" still holds true, but everyone underestimates the effects of slow local IO.
 
rylin said:
Memory is not the bottleneck, it's a finite resource that you've used up.
At that point (actually, before then in most cases), memory is paged to disk, which is the real bottleneck.

A healthy system is one which pre-emptively pages non-active data to disk, which means that when an app needs more memory, it can simply flush parts that are already on-disk (takes a few milliseconds).

Now, it's true that you could get more memory, but at this point you're likely to see a bigger performance boost per buck by getting better local storage.

If you have 15 apps open, and all of them are paging to disk, they'll be doing 5-6MB/sec each writing to the swap. Of course, the app your currently using that just requested more memory is fairly likely to be reading from the disk at the same time the writes are going on.. :)

The old adage of "no such thing as enough memory" still holds true, but everyone underestimates the effects of slow local IO.
Click to expand...
Yup. HDD access is the worst bottleneck in the system. ;)

There are instances where memory can be improved either by increasing the channels used, or capacity. Or both of course. :p Rather beneficial when it can be done and is applicable. But it doesn't apply as widely as improving HDD throuputs IMO. :)
 
VirtualRain said:
I can sorta understand the lack of slots on the Octo's... the CPU card just doesn't have much real-estate to work with... and 8 slots does give you 16GB capacity with cheap 2GB DIMMS. However, 4 slots on the quad is unforgivable given all the added real-estate they had to work with... It's bizarre. They could have easily rearranged the layout to accommodate 6 slots on the quad. :confused:
Click to expand...

I think this was a (cynical?) commercial decision by Apple to make sure that the four core doesn't overlap with the eight core. They also officially don't support 4GB sticks with the quad even though they work fine. Similarly they don't supply a quad mac pro with the W3570 3.2GHz Xeon even though it doesn't have any higher thermal envelope.

A W3570 based quad mac pro with 12GB of RAM in six slots should be cheaper than a 2.26GHz octo and with most applications would be much faster but from a commercial point of view would leave buyers in a bit of a quandary, even more so than now.

The quad mac pros are not designed as such, they are modified octos. They have the same case, power supply, slots etc (in contrast to Dell/HP/Sun etc who produce a specific workstation for single processors), this means
that Apple have to charge over the odds for quads and they are very expensive compared to the competition. I think this is why Apple would rather direct buyers to the octos and downplay the quads.
 
Gonk42 said:
I think this was a (cynical?) commercial decision by Apple to make sure that the four core doesn't overlap with the eight core.
Click to expand...

I tend to agree tho it's hard to know for sure without having a fly on the wall somewhere inside. But this assumption also leads to a conclusion of extreme incompetency on Apple's part. If it's like that then there should be "Mac Pro" with 12 or 18 RAM slots based on the xeon product line and "Mac SP" (Semi-Pro) with 6 RAM slots based on intel's desktop chips. The Mini and the iMacs wouldn't be overlapped and there would be a machine for every likely segment. The only reasons I can come up with as to why they did NOT do this is incompetency or that perhaps their marketing research discovered that the economy in combination with saturation levels couldn't support the diversity. Tho in the later case the applied (and ridiculous) price-hikes would make no sense at all. <shrug>

Still either way you look at it there's no reason except incompetency for the Mac Pro quad not to have at least 6 slots and the octad not to have 12 or 18. They offer 8... LOL!!! It's the wrong multiple and it's too few. What in the name of all that is good and binary were they thinking? This sort of incompetency unfortunately plagues Apple far too often IMO.

Oh well, they got the iPhone and iTouch right I think. :)
 
Okay--

What can I do for $200-300 (~price range of the RAM I considered) with my drive set up to get a big performance boost?
 
Move your scratch and files accessed off of the main drive and use a fairly speedy drive for the applications in question, so all your I/O isn't thrashing the same main drive. I will also agree that HDD I/O is the bottleneck in most machines, even if you're using more RAM than you actually need. Since you can now buy relatively fast 1 TB drives for under $100 apiece, you should be able to afford this. Many different people will recommend various drives for speed.
 
I am popping in a TB Hard Drive when I open the case to install the memory.

I'll keep my eyes open for a higher performance home drive in the future.
 
steveoc said:
Okay--

What can I do for $200-300 (~price range of the RAM I considered) with my drive set up to get a big performance boost?
Click to expand...

Yeah, you were on the right track in the first place.

Fortunately or unfortunately the scratch location doesn't seem to matter these days at all with drives as fast as they are. The PS way of using it's scratch is a mere fraction of what any modern (> 1TB) drive is capable of. For scratch performance these days my tests show that it's PS itself that is the bottleneck. This is also true for file saving. PS is a total dog in the worst sort of way in these two specific regards.

Anyway I dunno if $200 ~ $300 is enough or whatever but you need more RAM as you say you're running out. So that's point one! The other area of performance that can easily be improved as you know, is HDD I/O and the best price-performer right now is a multi-drive RAID0 setup. So those should be your two areas of focus.

If it were me, I would put 12GB RAM in 6x2GB first and then I would go for a 3-Drive RAID0 + Backup. Maybe the HD154UI from samsung or maybe the 1TB Blacks from WD at about $100 each and then I would cross my fingers for a few months till the 2TB drives became reasonable and then I would add one of those as a back-up solution. I would add it externally through a home made eSATA system given a concern over money.


.
 
Kinda Off Topic but...

I'm wondering when we move to Snow Leopard will the 09 Pro's support more than 32GB? 8GB x 8 or 6GB x 8, for a total of 64GB or 48GB. Just something I've been thinking about...
 
Ssd?

If HD IO is the true bottleneck perhaps a small SSD (with all apps and the OS put on the SSD) would boost the total performance more?

MaxUpgrades offers the 80GB Intel X-25 M plus 3.5" drive bay adapter for $349.
A 30GB OZC Vertex plus adapter is $159.

Perhaps the Vertex and 2 x 1GB extra RAM (for a total of 30GB SSD and 8GB RAM) might provide a bigger performance boost than just 16GB of RAM?

Also to keep in mind Intel is rumored to introduce new SSDs within a week or two.
Most expect same prices but double the capacity.
 
Tesselator said:
I agree. Unless you're trying to tune it for speed in mission critical fashion go for the 8x2GB. And i also agree that Apple gypped us on the RAM slots. The intel reference designs allow for 144GB of RAM in 18x8GB or 72GB in 18x4GB or 36GB in 18x2GB - notice also that 18 is a multiple of 3 and not 4. Jeezzz! Why is it that almost every aspect of the 2009 systems seem to piss me off? It's not just me... I don't feel that way at all about the 2006,~ 2008 systems.

Apple! Dang you! Hehehehe ;)
Click to expand...

You aren't the only one! I try to close my eyes and wish for my Quad 09 to have another 2 Ram slots but it never materializes. :D

8GB for me until the 4GB sticks drop about 200%. :mad:
 
I'll address the I/O drive situation in a couple months.

There is no doubt in my mind that the RAM will give me a significant boost. I ordered 4 X 2. That should be good for quite awhile.

I think what I'll do is grab one or two 1 TB drives in the future and Stripe raid them. That, as mentioned before, leads an need to provide 2 TB of backup.

If SSD come down significantly by that time I'll give them a look. I'll need something fairly big as my App + Lib + System > 80 GB.
 
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