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Corsair High End MBP Memory

Low Latency Memory Performance on MacBook Pro

Memory bandwidth has a critical impact on the performance of many advanced computing applications. By developing a memory module with low latencies specifically tuned for Mac computers, we are able to provide significant performance improvements when using many common applications. This paper will present a selection of these test results.
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The "higher performance" they are claiming is as a result of lowering the CAS latency from 5 to 4. (as you know by now, the memory bus is locked at 667 MHz on Core2Duo Macs.)

Nobody to my knowledge has ever shown that Macs will automatically adjust motherboard timings to take advantage of lower latencies (and equally, nobody has proved they can't either -- Apple is silent on the matter of latency and performance)

Corsairs link to the white paper outlining this is a dead link at this time :rolleyes:
 
CanadaRAM said:
The "higher performance" they are claiming is as a result of lowering the CAS latency from 5 to 4. (as you know by now, the memory bus is locked at 667 MHz on Core2Duo Macs.)
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The Corsair modules also have tweaked subtimings for MAC computers so that's where you will see the small performance increase over other regular CAS 4 modules of the same speed. I wouldn't mind buying the Corsair RAM myself if it was only like $20 more for the 2x2GB kit vs the regular kits but I'm not going to pay twice as much.
 
I attached the pdf to this post:

https://forums.macrumors.com/threads/452462/

I read some forums at mac-forums where it appears a Corsair employee posted. (I posted the link somewhere in one of the other memory discussions, I don't remember where at the moment.)

From what I have gathered. To be labeled Mac Memory, you have to go to Apple to have your memory pass the apple benchmark tests.

This is why you can buy Kingston, Crucial, etc.. memory labeled Mac Memory for $100. Or buy the same exact memory not labeled Mac Memory for $70.

The former passed the Apple benchmarks, The latter did not supposedly.

FYI: They say retail price is $160. That means newegg and others will have it for $120 or something like that. the only place I can find right now to buy it is: NCIX
 
From what I've read. Corsair claims that there are sub-timings that help with the improvement. So, if G.Skill had the same sub-timings then yes, but my guess is no since it is not labeled as "mac" memory.

I went and bought the G.Skill memory. I figured it would take a while for the price of the Corsair to come down to it.
 
scott9s said:
From what I've read. Corsair claims that there are sub-timings that help with the improvement. So, if G.Skill had the same sub-timings then yes, but my guess is no since it is not labeled as "mac" memory.

I went and bought the G.Skill memory. I figured it would take a while for the price of the Corsair to come down to it.
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Please do post some of the performance gains test just like the corsair's PDF if possible.
Just the Zip test might do.

thanks :)
 
I'm looking for a good deal on 4GB 800mhz CAS4 memory. Has anyone bought any of this for the Santa Rosa Chipset MB/MBPs?
 
YoYoMa said:
I'm looking for a good deal on 4GB 800mhz CAS4 memory. Has anyone bought any of this for the Santa Rosa Chipset MB/MBPs?
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I've seen others mention that the current MBP's won't support 800Mhz RAM so it may or may not recognize it and be able to downclock it to 667Mhz.
 
YoYoMa said:
I'm looking for a good deal on 4GB 800mhz CAS4 memory. Has anyone bought any of this for the Santa Rosa Chipset MB/MBPs?
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You don't want 800 MHz memory. It is of no benefit and you increase the risk of it not working. The SantaRosa Macs (and Penryn Core2Duos) are locked down at 667 MHz memory bus speed.

Here's the PDF is that what you wanted:
http://att.macrumors.com/attachment....9&d=1205335187
Click to expand...
Interesting - they tested on a pre-Santa Rosa machine. That's a strange choice.

Performance increase vs. an equal amount of CL5 memory was 19% and 9%, (not the 28% figure bandied about) The 28% result is a canard-- it is comparing 4 Gb RAM against 1 Gb RAM

XBench test results should be dismissed out of hand. They are synthetic benchmarks that bear no resemblance to the real world. (That was amply displayed a few years ago when XBench showed a doubling of memory bandwidth for 128-bit access in the iMac G5, and real world testing showed 0% improvement)

The tests under VMWare Fusion -- 7% improvement in WinRAR

Bootcamp: shows minimal improvements half of a percent on Everest memory benchmark composite, 4% on WinRAR.

I have a few questions about the test. Why no SantaRosa? Why test on a machine that can't access the full 4 Gb?
What was the methodology for the testing? Were the effects of hard drive speed and caching accounted for? Some of the improvements are well withing the range of other variable.

(I can easily make a test show 25% difference in speed simply by running it once on a fresh hard drive and them a second time on a nearly full hard drive)

The question hinges around whether or not Apple's firmware will allow the motherboard to automatically sense and adjust the memory bus timings to the RAM SPD values. If it can, then the question is how much real world advantage does that give you?
 
sevimli said:
I have been using 2x2gb OCZ 800mhz ram for months. No problem at all.:cool:
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Which tells us that you used it on a SR but pre-penryn MBP. Unfortunately, the Penryn MBP, which still uses SR, no longer supports 800mhz memory. Several forum members including myself had it waiting for the MBP release, and it did not work :( Got it swapped for some 667 and worked just fine.

So, to YoYoMa, if you have a SR MBP prior to the penryn revision, you're fine, but if you have a penryn model, don't get 800.
 
DocSmitty said:
Which tells us that you used it on a SR but pre-penryn MBP. Unfortunately, the Penryn MBP, which still uses SR, no longer supports 800mhz memory. Several forum members including myself had it waiting for the MBP release, and it did not work :( Got it swapped for some 667 and worked just fine.

So, to YoYoMa, if you have a SR MBP prior to the penryn revision, you're fine, but if you have a penryn model, don't get 800.
Click to expand...

It doesn't make any sense why they would lock it down on the Penryn based machines if it worked on the pre-penryn Santa Rosa models. Penryn still uses the same Santa Rosa based motherboard as the previous gen.

Still good info to be aware of though as maybe it will keep a few people from having the headache of trying it out for themselves all to find it won't work.
 
CanadaRAM said:
The question hinges around whether or not Apple's firmware will allow the motherboard to automatically sense and adjust the memory bus timings to the RAM SPD values. If it can, then the question is how much real world advantage does that give you?
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EXACTLY! No one ever seems to be able to answer this question, I almost routinely find the answer to be someone saying that it "probably" or "shouldn't" detect and use the lower timings. Has anyone ever tried and tested the Cas 4 ram by G-Skill or any other manufacturer?
 
Hey. I'm about to make a RAM purchase for my Penryn MBP and am going to buy CAS4 from someone. Is there a consensus as to who makes the best CAS4 memory for macs? I don't mind paying an extra 10 or 15 bucks if the memory is better. Some suggestions would be appreciated. Thanks.

PS - When 4GB laptop sticks are available, will the Penryn MBP accept them?
 
miykael81 said:
EXACTLY! No one ever seems to be able to answer this question, I almost routinely find the answer to be someone saying that it "probably" or "shouldn't" detect and use the lower timings. Has anyone ever tried and tested the Cas 4 ram by G-Skill or any other manufacturer?
Click to expand...

Corsair wouldn't be advertising the RAM to run at tighter 4-4-4-12 timings on a MAC if MAC's didn't actually detect at those lower timings in the SPD.
 
YoYoMa said:
Hey. I'm about to make a RAM purchase for my Penryn MBP and am going to buy CAS4 from someone. Is there a consensus as to who makes the best CAS4 memory for macs? I don't mind paying an extra 10 or 15 bucks if the memory is better. Some suggestions would be appreciated. Thanks.
Click to expand...

There are only a couple of brands I've seen offering CAS 4 SO-DIMM modules rated at 667Mhz. G. Skill is one of them. I just bought the OCZ 800MHz 2x2GB kit though which is rated at 5-5-5-15 but will detect at 4-5-5-13 when running at 667Mhz. I got them for only $69.99 after rebate - $50 promotion discount for applying for a RevolutionCard at Buy.com. So the kit only cost me $9.99 after rebate.
 
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