Modern CPUs & systems do not have a FSB. Regarding the latency:
http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3/5
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32GB (2x16GB) not yet being sold?
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http://www.anandtech.com/show/4503/sandy-bridge-memory-scaling-choosing-the-best-ddr3/5
I read the handful of these threads around the 'net and it burns me every time when someone asks "what on earth do you need that much memory for"!
Well let me give just one of many examples. I am a web developer. I strongly prefer to develop in OSX and I strongly prefer a laptop because I'm very mobile. Very often due to the nature of my development, I need to test things out in multiple browsers, in multiple operating systems. This means having virtual machines open for WinXP, Win7, Win8, possibly older versions of OSX w/ older versions of Safari, etc etc. You get the point.
Now, giving a single core to each VM isn't a problem. When you are just running a browser you can live with that all fine and dandy. But what you can't live with is running out of memory and *SWAPPING TO THE DISK*. That creates a performance impact many orders of magnitude worse than merely running with insufficient CPU resources. So to avoid that you give a couple gigs of RAM to each VM, say 2GB to be safe. In addition to this, I have an IDE and JVM's (java) running locally as part of my development. Currently the application I spend my most time on requires two JVM's running concurrently, each consuming ~2GB
So to summarize:
3xVM's @ 2GB each = 6GB + Vmware Fusion overhead
2xJVM's @ 2GB each = 4GB
IDE = 1GB
Chrome, Safari, FF = ~512MB each = 1.5GB
So right there we are sitting at 12.5GB. Now add in all your auxiliary programs (Email, IM, Photoshop, whatever) and you quickly bump up against the 16GB maximum possible amount of RAM currently available.
Instead I have to resort to shutting down, starting up, shutting down, starting up my VM's. That gets old, even if they are running off an SSD (and thus starting quicker).
Just because you cannot personally envision a use case, DO NOT ASSUME THERE ARE NONE. That's only one. If you need more, then I'll be happy to oblige. Despite the potentially crazy prices, there is in fact a niche market out there that would be happy to pay for it!
Well let me give just one of many examples. I am a web developer. I strongly prefer to develop in OSX and I strongly prefer a laptop because I'm very mobile. Very often due to the nature of my development, I need to test things out in multiple browsers, in multiple operating systems. This means having virtual machines open for WinXP, Win7, Win8, possibly older versions of OSX w/ older versions of Safari, etc etc. You get the point.
Now, giving a single core to each VM isn't a problem. When you are just running a browser you can live with that all fine and dandy. But what you can't live with is running out of memory and *SWAPPING TO THE DISK*. That creates a performance impact many orders of magnitude worse than merely running with insufficient CPU resources. So to avoid that you give a couple gigs of RAM to each VM, say 2GB to be safe. In addition to this, I have an IDE and JVM's (java) running locally as part of my development. Currently the application I spend my most time on requires two JVM's running concurrently, each consuming ~2GB
So to summarize:
3xVM's @ 2GB each = 6GB + Vmware Fusion overhead
2xJVM's @ 2GB each = 4GB
IDE = 1GB
Chrome, Safari, FF = ~512MB each = 1.5GB
So right there we are sitting at 12.5GB. Now add in all your auxiliary programs (Email, IM, Photoshop, whatever) and you quickly bump up against the 16GB maximum possible amount of RAM currently available.
Instead I have to resort to shutting down, starting up, shutting down, starting up my VM's. That gets old, even if they are running off an SSD (and thus starting quicker).
Just because you cannot personally envision a use case, DO NOT ASSUME THERE ARE NONE. That's only one. If you need more, then I'll be happy to oblige. Despite the potentially crazy prices, there is in fact a niche market out there that would be happy to pay for it!
I don't get what you mean?
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So your saying having all those applications open at once will require 32GB of ram?
Not even having all programs open. I'm not even doing anything super-heavy right now (2VMs working in Visual Studio while encoding a video). I put my Mac to use.
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My Early-2011 Sandy Bridge i7 Quad-Core MBP supports also 32 GB RAM:
http://ark.intel.com/products/50067/Intel-Core-i7-2720QM-Processor-6M-Cache-up-to-3_30-GHz
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More in the range of ≈ 800 US$ (x2 = 1600 US$):
https://www.macrumors.com/2011/03/09/16-gb-ram-upgrades-for-new-macbook-pros-now-available/
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No, the CPU is much faster than the RAM.
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Modern processors have no FSB, AFAIK. And the CAS latency is only responsible for the error correction on the RAM module. Has nothing to do with the bus speed.
I agree 100 %. In my tests RAM cache improves the read performance for larger (and smaller) files substantially. A read operation from the RAM cache is around 5 times faster than a direct read operation from a HDD/SSD.
hardwickj & Doward, thanks for your posts! I agree, because i've a similar problem.
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Good for you.
My 17" MacBook Pro is my baby. I've got lots of other very nice machines around, but I end up always using the 17" because it's everything I generally need in one place. I removed the optical drive in favour of a second hard drive. And while 16GB gives me enough to work with, I would use 32GB if it were an option...
I sure hope 16GB DDR3 SODIMMs arrive, though I'm skeptical as it seems like this is an old thread.
I sure hope 16GB DDR3 SODIMMs arrive, though I'm skeptical as it seems like this is an old thread.
Would this work in a MBP?
http://www.provantage.com/crucial-technology-ct2k16g3ersld4160b~BCIAL6UN.htm
I am currently in the market for a MBP but it *MUST* have 32GB of memory to run the VMs I need.
That site has got all its specs wrong.
Crucial only makes 2x16GB 1866MHz ECC chips for the nMP. It won't work in an MBP, because it's an ECC type.
The right specs: http://www.amazon.com/Crucial-2x16GB-DDR3-1866-Systems-CT2K16G3R186DM/dp/B00GEC3ZJQ