This might be a really dumb question but will it make a big difference if I add 16gb (8gb x 2) to the empty two slots on my iMac or would it be just as fast adding 8gb (4gb x 2)? I hear different things about RAM and I have heard in some situations if you have different size RAM there is not a big speed increase. Also, how bad (or good) is PNY ram? Normally I would buy Crucial but I have some gift certificates and Crucial isn't an option at where I want to buy it.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
PNY is good ram. They all get the chips that go on the modules from the same suppliers there is next to no difference in any of the manufacturers. If you are not doing anything causing a lot of memory swapping the 4x4 in the machine will perform the same as the higher amount. It is when you exceed the ram in the machine and it has to swap to disk it slows you down. Do you use any programs that need large amounts of memory, like editing videos or loading large sound samples.
I am not certain there, I know with different sized modules on the same channel you lose 3% I think it is I have read in the past, as the dual channel will not function like that. When you put matched modules larger size I have no idea if the dual channel will still function. If doing all four the size being equal, the dual channel, I know from experience doing it still functions. I would need to be able to see a pc boot with the memory configured that way, then it will tell you if it is configured for dual channel. You can see it in the messages as it initializes the ram when mis-matched modules are present you do not see it say the dual channel. If you need that much ram it does not matter if you do lose the 3% anyways. Go with what you can afford for it, if not a pressing need for more, then no sense in it.
Edit: Just had to know. I have such a machine it occurred to me to reboot my Debian server but Google found me the command to use in the first hit so no reboot necessary.
Code:
root@haswell:/home/seeder1# dmidecode -t 17 |grep Channel
Locator: ChannelA-DIMM0
Locator: ChannelA-DIMM1
Locator: ChannelB-DIMM0
Locator: ChannelB-DIMM1
root@haswell:/home/seeder1# dmidecode |grep Size
Runtime Size: 64 kB
ROM Size: 8192 kB
Installed Size: 128 kB
Maximum Size: 128 kB
Installed Size: 512 kB
Maximum Size: 512 kB
Installed Size: 3072 kB
Maximum Size: 3072 kB
Size: 4096 MB
Range Size: 4 GB
Size: 2048 MB
Range Size: 2 GB
Size: 4096 MB
Range Size: 4 GB
Size: 2048 MB
Range Size: 2 GB
Range Size: 12 GBAs you can see matched pairs of 2gb and 4gb for 12gb total running in dual channel the Channel A & B in the first output.
Last edited:
Whoever has the cheapest price, for the most part RAM is a commodity part. The only difference really is the name on the label, the chips themselves are made by the low number of companies in the business of making them. Most brands are just a repacking of them chips onto standard board designs.
Keep them in pairs. The pairs can be different.
You have 2x4GB. You can add 2xanything in the empty slots. So you add 2x4 or 2x8. Assuming it is compatible RAM there is no difference in RAM speed. But the Mac will run better with more RAM - how much depends on your workload.
Who knows get something like iStat menus and check your swap size on a regular basis. If you see it using a lot of swap and the machine is feeling a little slow opening things at that time you do, then you could probably use more memory.
"dual profile" should mean that the memory will be less sensitive to differences in chipsets - and that should result in fewer compatibility issues.
Crucial is a good name, they stand behind what they make. Not like some of the other memory sellers who don't make the memory sticks that they sell.
Get the sticks that Crucial recommends for your model Mac. You should be fine.
Crucial is a good name, they stand behind what they make. Not like some of the other memory sellers who don't make the memory sticks that they sell.
Get the sticks that Crucial recommends for your model Mac. You should be fine.
I have the exact same iMac as you, and added 2x8GB sticks for a total of 24GB. Runs great, and a huge improvement from 8GB. For photo-editing it occasionally uses all 24GB. Go for it. My sticks are Crucial, but I don't see why PNY wouldn't be fine provided it is the exact same spec
Here is my typical memory usage, having 24GB. You can see that 16GB would mean I would have to use swap memory. YMMV, obviously
Not as obvious as you might think.
If you have more memory, your Mac uses more.
Conversely, if you have less memory, your Mac uses less.
Swapping may come into play, but not necessarily.