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iMac Geekbench 2019 Before and After RAM upgrade. Interesting!

K

kenfused

macrumors member
Original poster
Mar 20, 2009
40
1
So I got a 2019 27" 5K iMac, 3.7Ghz Core i5 machine. 3TB Fusion and 8GB RAM

After transferring my stuff over from my old mac, I got a single core Geekbench4 score of 5580, then 21718 multicore.

I added in 16GB (8GB x2) of Crucial Ram, and based on some things I read, I took out the 4GB X2 stock RAM and put in the 8GB in those slots, and the stock 4GB RAM into the originally empty slots.

Ran Geek bench again and got surprisingly LOWER results 5332, and 23665 Multicore. Ran it over and over wondering why the single core scores dropped.

Then decided to put the original RAM in the original slots they came in and the Crucial 8GB Ram into the empty slots.

Got Single Core score of 6009, and Multicore 23529

Seems like a big difference and only thing that changed was the slots the RAM were in!
 
There is probably something else going on. No way that the differences in RAM should give a difference from 5332 to 6009.

Run the benchmark after a reboot, with all applications closed (not just the windows), make sure nothing else is running (indexing, Time Machine backup, etc.); also quite important: same thermal condition. Hot CPUs will get throttled down. So running in a hot environment may give lower results, as well as repeated runs.

You can also check the running frequencies of the modules, although the practical implications should be minimal.
 
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I thought we were supposed to put the new ram in the old ram slots as that gives you the read out in “about this iMac” and under memory of new ram on top two rectangles and old ram on bottom two?
 
aman88 said:
I thought we were supposed to put the new ram in the old ram slots as that gives you the read out in “about this iMac” and under memory of new ram on top two rectangles and old ram on bottom two?
Click to expand...

Who cares which boxes the RAM appears in? Is there a functionality reason? Versus the (small) risks in moving them all about and not getting good connections etc or breaking them... I just shoved mine in the empty slots.
 
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wardie said:
Who cares which boxes the RAM appears in? Is there a functionality reason? Versus the (small) risks in moving them all about and not getting good connections etc or breaking them... I just shoved mine in the empty slots.
Click to expand...

That is just what a saw online that having the higher gb ram in that order it will work better. Not sure if there is nay truth to that.
 
aman88 said:
That is just what a saw online that having the higher gb ram in that order it will work better. Not sure if there is nay truth to that.
Click to expand...

I doubt it. What does matter though is that you get the identical pairs of memory cards lined up in the right pairs of slots (if they are different pairs) so they all work in dual-channel mode. Otherwise you may sacrifice a bit of throughput performance.
 
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wardie said:
I doubt it. What does matter though is that you get the identical pairs of memory cards lined up in the right pairs of slots (if they are different pairs) so they all work in dual-channel mode. Otherwise you may sacrifice a bit of throughput performance.
Click to expand...

How do you know you did that? Currently
Mine has, in the about this Mac and memeory section, the two 8 gb owc ram sticks on top left and right and the original two 4 gb sticks on the bottom left and right.
 
aman88 said:
How do you know you did that? Currently
Mine has, in the about this Mac and memeory section, the two 8 gb owc ram sticks on top left and right and the original two 4 gb sticks on the bottom left and right.
Click to expand...

Well... i just didn’t move the apple stock 8GB from where it was (slots 1&3 I think, its a 2017 iMac 27”) and put the extra pair I bought in the two free slots. I can’t remember which way round the macOS system report shows it.
 
wardie said:
Well... i just didn’t move the apple stock 8GB from where it was (slots 1&3 I think, its a 2017 iMac 27”) and put the extra pair I bought in the two free slots. I can’t remember which way round the macOS system report shows it.
Click to expand...

So it’s supposed to alternate? Same ram in 1 and 3 then same ram in 2 and 4 slots?
 
aman88 said:
So it’s supposed to alternate? Same ram in 1 and 3 then same ram in 2 and 4 slots?
Click to expand...

Pretty sure you have to alternate.

When I ran the benchmarks, Geekbench 4 was the only thing running too.
 
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