Resolved Different RAM modules

[poiihy]

I have an iMac and MacBook Pro, both which can work with the same memory. After solving my MBP's crashing problem (bad RAM) I had to share the 4GB (2x2GB) from my iMac with my MacBook Pro, but 2GB in Mavericks/Yosemite is so very painfully slow. I plan to buy an 8 GB kit (2x4GB) and share that between the iMac and MBP so that both have 6GB (vs one having 8 and other having 4) but i have some questions. Does both RAM modules have to be the same clock speed? Would it be better to Buy an 8GB kit so both computers have 6GB, or would it be better to just by a 4GB kit so both computers have 4GB? 4GB would be cheaper but maybe slower than 6GB on Mavericks/Yosemite. Also where can I find the best deal on RAM? RAM is quite expensive (almost as much as an SSD )

 

[simonsi]

Consider that while your MBP has only 2 slots, your iMac has 4 slots so you may be able to get an additional 2x 2GB for the iMac quite cheap and only spend real $$$ on the MBP 2x 4GB.

Mixing stick sizes definitely has a perf overhead vs running the same stick in both slots, I haven't tried asymmetrical speeds....

 

[poiihy]

Consider that while your MBP has only 2 slots, your iMac has 4 slots so you may be able to get an additional 2x 2GB for the iMac quite cheap and only spend real $$$ on the MBP 2x 4GB.

Mixing stick sizes definitely has a perf overhead vs running the same stick in both slots, I haven't tried asymmetrical speeds....

It's a late (or early?) 2009 imac and it only has two RAM slots.

 

[simonsi]

It's a late (or early?) 2009 imac and it only has two RAM slots.

Ah nuts, sorry.

 

[poiihy]

Mixing stick sizes definitely has a perf overhead vs running the same stick in both slots, I haven't tried asymmetrical speeds....

How bad is it to use unbalanced amounts of RAM? Would it be a noticeable performance hit or would it be very minuscule?

 

[simonsi]

How bad is it to use unbalanced amounts of RAM? Would it be a noticeable performance hit or would it be very minuscule?

Around 10% speed hit normally, no idea on the effect of mis-matched speeds, probably make either no difference or give you a memory failure beep.

 

[cjmillsnun]

Don't share RAM like that. You'll get a performance hit and also get an increased likelihood of errors.

Put the larger amount of RAM in the Mac you use the most.

IMO RAM is cheap. £130 buys you 4 4GB Crucial sticks, giving you 8GB on both Macs.

 

[poiihy]

So I suppose I will just buy a separate 2x2GB kit (4GB) so both have same (parallel) modules.

Does anyone know what happens if you mix different speeds?

 

[poiihy]

I have another question(s).

The iMac, according to Apple's page, takes 1067MHz RAM, while the MacBook Pro takes 1600MHz RAM. (I have 1067MHz RAM in the MacBook Pro now and it works.) Is that the maximum? If so then anything higher than 1066MHz won't work in the iMac, ruining the idea of sharing RAM making 6GB each.
Should I get only 1600MHz RAM for the MacBook Pro, or should i get anything between 1067 and 1600? Does a higher RAM speed make much difference?
Also, is it worth it to get 8GB or should I just get 4GB? 4GB is cheaper but 8GB may be faster. There is no point in getting more RAM for future OS's as the computer probably would not support the next OS's anyway, and Yosemite will last a good four years (at least). So how much faster is 8GB vs 4GB in Yosemite? Is it worth the extra cash?

 

[Samuelsan2001]

Use this guide

https://forums.macrumors.com/threads/1756865/

Use this for an estimate of how much RAM you need i8n each computer.

Use the fastest RAM you can in each and don't mix speeds.

More RAM only speeds up your computer if you don't have enough to do what you need to so more RAM is not nessecarily more speed.

 

[poiihy]

https://forums.macrumors.com/threads/1756865/

Use this for an estimate of how much RAM you need i8n each computer.

Use the fastest RAM you can in each and don't mix speeds.

More RAM only speeds up your computer if you don't have enough to do what you need to so more RAM is not nessecarily more speed.

This is no help to me at all.
All I really need is 4GB, but I've heard people getting better performance in Mavericks/Yosemite with 6 or 8GB. How much better is it? Is it worth the cost? If it is not that much faster then I'd stick with 4.
My MacBook Pro is already more than 5 years old, and it supports 6 versions of OS X (10.5 - 10.10). The next release (OS XI?) will probably not be supported on my system.

Also, the iMac takes 1067MHz RAM according to Apple's site. Does this mean the maximum?

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Ok, I think I know what to aim for now

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Around 10% speed hit normally, no idea on the effect of mis-matched speeds, probably make either no difference or give you a memory failure beep.

I've heard that if you mix speeds, the faster one(s) will down-clock to match the slowest one.

 

[Samuelsan2001]

Really??

This is no help to me at all.
All I really need is 4GB, but I've heard people getting better performance in Mavericks/Yosemite with 6 or 8GB. How much better is it? Is it worth the cost? If it is not that much faster then I'd stick with 4.
My MacBook Pro is already more than 5 years old, and it supports 6 versions of OS X (10.5 - 10.10). The next release (OS XI?) will probably not be supported on my system.

Also, the iMac takes 1067MHz RAM according to Apple's site. Does this mean the maximum?

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Ok, I think I know what to aim for now

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I've heard that if you mix speeds, the faster one(s) will down-clock to match the slowest one.

I thought I made myself quite clear.

More RAM doesn't mean more speed unless you are maxxing out your RAM. So yes it will perform better if you have a lot open at one time, no it won't if your use is light hence my link to meisters excellent guide.

RAM speed does make a difference.

Mixing RAM speeds is not a good idea.

If your macbook pro is that old then it only supports 1066mhz as well and will downclock any faster RAM.

OWC gives you all the info you need on what RAM for what product...

http://eshop.macsales.com/MyOWC/Upgrades.cfm?model=360