Late 2015 iMac: New ram of same specs, not playing nice with old

[maves]

Hello,

I recently bought 2x8gb @1867ghz sticks of RAM to add to the 16gb (also 2x8gb @1867ghz) that is in my late 2015 iMac.

Despite tracking down RAM that is the same brand, clock speed, and latency; when installed together, the system shows the speed as 1333ghz.

I've attached a picture of the old and new RAM. Is there something I'm missing? Is there any reason these sticks should not be completely compatible?

[/url][/IMG]
https://imgur.com/dhgDVM1

Thanks

 

[droog]

Try using the new ram independently of the original ram. If it boots to 1867, then their is a good chance the imac down clocks while running quad channel. If this is so, you'd need 2x16 to reach 1876. You'll probably be fine at 1333 unless you are doing a bunch of gaming.

 

[robbier]

I would also try a PRAM reset and then see if the RAM is running at the proper speed.

 

[nambuccaheadsau]

Where did you get the modules? OWC and Crucial for me.