Is it true that I have to get the exact same speed RAM for Macs or else (what?)

[lkar]

Near the middle of this thread: https://www.reddit.com/r/mac/comments/hxdkhu

I'm running Debian Buster Xfce on my 2009 iMac with a 8Gb ram upgrade without much trouble.

One thing to note if upgrading the ram: Unlike many other device these won't down-clock newer ram to their max supported speed. this means either buying more expensive ram that is a perfect match for the device or editing the spd data of the sodimms to match what the device supports

I have this iMac:

I was planning to get 2 x 4 gb 1333mhz sticks and put one in my other (faster) imac and 1 stick in this 2009 iMac, will that still work if this iMac uses 1067 mhz ram?

On a PC it would be no problem as the RAM would just run at the slowest speed of all the sticks that are in there (which is 1067 mhz), but according to the reddit thread/post above i have to get the 1066 mhz ram because it is a mac? please let me know, i prefer to get it right the first time i upgrade the RAM on my imac

 

[DarkPremiumCho]

I'm afraid 1333MHz sticks won't work. According to this, you'll need 2GB or 4GB RAM SO-DIMMs of 1066MHz DDR3 SDRAM in each slot and meeting all these criteria:

• PC3-8500
• Unbuffered
• Nonparity

But that's just my conclusion solely based on the Apple's document. Your results may vary.

 

[lkar]

I'm afraid 1333MHz sticks won't work. According to this, you'll need 2GB or 4GB RAM SO-DIMMs of 1066MHz DDR3 SDRAM in each slot and meeting all these criteria:

• PC3-8500
• Unbuffered
• Nonparity

But that's just my conclusion solely based on the Apple's document. Your results may vary.

Ok, but that doesn't answer my questions in the OP at all, so the questions in my original post still stands.

If anyone has personal experience putting in faster RAM than what is listed in the stock specs and the results then please let me know, thank you.

 

[kschendel]

I've added RAM to a couple different iMacs of various vintages, and one was early 2009. I'm 99% sure that I didn't speed-match, and if the sticks aren't matched, it shouldn't matter which one is the faster and which the slower. I'm very skeptical that faster RAM would be a problem.

 

[hobowankenobi]

As I recall, it will downclock and run without issue...or won't work at all, in which case you will get 3 beeps and no boot, if it is beyond the spec of the memory bus on that Mac. If you are planning on 3 sticks of RAM you don't have to pay attention to which slots for Core Duo:

i5 and i7 Quad Core iMac computers come with both top memory slots populated. These computers will not start up if only a single DIMM is installed in any bottom slot; these computers should operate normally with a single DIMM installed in any top slot. Core Duo iMac computers should operate normally with a single DIMM installed in any slot, top or bottom. ("Top" and "bottom" slots refer to the orientation of the slots in the pictures below. "Top" refers to the slots closest to the display; "bottom" refers to the slots closest to the stand.)

Apple Info here.

It will work. Unless it doesn't.

If it were me and I had the RAM, I would try it. If I were buying RAM for the iMac I would buy the correct spec.