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What’s The Difference Between PC And Mac RAM?

Posted by nik on November 6, 2018

ramComputers are computers, right? Sure, the operating systems are different and they use different design philosophies, but surely the RAM that goes into a PC and the RAM that goes into a Mac are the same. The answer, helpfully, is “maybe.” At one point in the not-so-distant past, Mac and PC memory sticks were generally not very compatible. However, the two platforms have come closer together in many areas, memory among them. However, the basic truth about Mac and PC memory remains this: picking out proper Mac memory is determined by model while on a PC it’s determined by motherboard.

If you built your PC yourself, you shop for memory based on what the motherboard supports. If the motherboard’s documentation states it will run DDR3 of either 800, 1066, 1333 or 2200, you’ll most likely go with middle-of-the-road (as most people do) 1333 memory, install it and that’s that.

You can’t buy a logic board independently for any new or currently-produced Mac computer, so the way memory is bought for those systems is by model, such as “for iMac”, “for Mac Pro” and so on.

The “forgiveness” of PC memory

PCs are “more forgiving” when it comes to memory than Macs are. For example if you put in mixed DDR3 memory in a PC, such as one 1066 stick and one 1333 stick, as long as the motherboard supports it, both sticks will simply run at the “lower” stick speed, in this case 1066.

Disclaimer before continuing: Don’t use mixed memory in your PC. Use the same speed for all your RAM sticks, and if possible use the same brand as well.

If you try to do the mixed memory thing on a Mac, OS X either won’t “like it” very much, or the Mac simply won’t boot. Some Macs are very particular almost to a fault when it comes to RAM speed; that’s the way Apple designs their computers.

Could you put PC RAM in a Mac and have it work?

In some instances you can, but more often than not the answer is no. Some will say they’ve done it and their Mac runs great, while others will say all the machine did on power-up is show a blinking power LED on the front, no picture, and no boot until they used “all-correct” memory.

The general rule of thumb is to always use Mac-specific memory for your Mac. That doesn’t mean you have to buy it from Apple specifically, but it does mean the memory must be listed as being compatible with your specific Apple system. If not, you’re just figuratively rolling the dice, you’ll probably lose, and your Mac won’t work.

Does Mac memory cost more?

Yes, and this is usually because a Mac requires fully buffered ECC (error-correcting) memory as a hardware system requirement.

However..

The price difference between Mac and PC memory isn’t nearly as wide as one would think.

8GB of Kingston PC2 5300 fully buffered Mac memory at the time of this writing is $19.49.

8GB of like-type Crucial PC2 5300 memory for PC is $88.99.

What you pay for memory directly depends on what type it is. Why does PC2 5300 cost so much on the Mac side? I honestly have no idea, but you will spend almost $100 to get that 8GB.

2 thoughts on “What’s The Difference Between PC And Mac RAM?”

y124y1hrh81h124 says:
Also relevant: the Mac memory has a thermal sensor which PC RAM lacks unless you are incredibly lucky. Server grade RAM does but usually (in fact 99% of the time) it will be RDRAM or some other variant which has totally different layout and WILL NOT WORK AT ALL in either a PC or Mac.
You can if you are incredibly brave reprogram a stick “hot” by using two in an old machine and copy the relevant bits from one to the other (it will typically work once booted) and something like SPDtool but this is a bad idea and may result in a brick if its done wrong and checksum gets mangulated.
Also technically you’d be breaching Apple’s IP but its not like they would ever find out unless you went for warranty repair and they did a check.
(so keep the old RAM handy!)
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Trendless says:
Two reasons: supply and demand, and 4gb ddr2 sticks were unusual and rare,
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