iMac acting up

[roman726]

So my iMac gave me a 3 beep sound about a week ago indicating that something was wrong with the RAM, I went ahead and ordered a set of 2 8gb sticks from OWC after they arrived I went ahead and installed them; after the install my iMac started to act up by randomly restarting while using it or during stand by.
Someone gave me an idea about removing one of the sticks to see if the problem would stay and to narrow it down to a defective stick but here's the catch while only using one of them I have not encountered any issues and I have been flip flopping from one to the other without any problems but as soon as both of them are installed the problem begins is like they are not compatible with one another even though they are paired. Could that be the case any other ideas as to what could be the issue, So far I've performed the NVRAM reset, SMC and a diagnostic by holding down D while powering up or after a restart and according to the diagnostic everything works fine. Thanks in Advance

iMac 5K 27"
Mid 2015
3.3GHz i5
15,1
High Sierra 10.13.6

 

[Fishrrman]

"Someone gave me an idea about removing one of the sticks to see if the problem would stay and to narrow it down to a defective stick but here's the catch while only using one of them I have not encountered any issues and I have been flip flopping from one to the other without any problems but as soon as both of them are installed the problem begins"

That was a good course of action to track down the problem.
Sounds like the problem might be with the -slot-, not with the RAM.

According to this page:
https://www.datamemorysystems.com/a...k462ll/a-retina-5k-late-2015-memory-upgrades/

... the mid-2015 iMac will accept 16gb DIMMs.

If you cannot resolve the problems any other way, my suggestion would be:
- install 1 16gb DIMM into the "known good" slot
- leave the other "known defective" slot EMPTY.

Granted, it doesn't "repair" the bad slot, but simply "works around" it.
Unless you want to spend $$$ (might involve replacing the motherboard to correct the problem with the slot)... it could be "the best way out" of the situation.

A suggestion:
Try using an 8gb DIMM in the good slot, and use one of the -original- Apple DIMMs in the "flaky slot".
Does doing this change anything?

 

[roman726]

"Someone gave me an idea about removing one of the sticks to see if the problem would stay and to narrow it down to a defective stick but here's the catch while only using one of them I have not encountered any issues and I have been flip flopping from one to the other without any problems but as soon as both of them are installed the problem begins"

That was a good course of action to track down the problem.
Sounds like the problem might be with the -slot-, not with the RAM.

According to this page:
https://www.datamemorysystems.com/a...k462ll/a-retina-5k-late-2015-memory-upgrades/

... the mid-2015 iMac will accept 16gb DIMMs.

If you cannot resolve the problems any other way, my suggestion would be:
- install 1 16gb DIMM into the "known good" slot
- leave the other "known defective" slot EMPTY.

Granted, it doesn't "repair" the bad slot, but simply "works around" it.
Unless you want to spend $$$ (might involve replacing the motherboard to correct the problem with the slot)... it could be "the best way out" of the situation.

A suggestion:
Try using an 8gb DIMM in the good slot, and use one of the -original- Apple DIMMs in the "flaky slot".
Does doing this change anything?

Thanks for the response, as of right now I'm using it like that with only one 8gb stick on the first slot. I've already contacted OWC and they are replacing the ones I have. The funny thing is that one stick will work on any of the slots so they are all working it only fails when both of them are installed, to me is kind off like they can't work together something might be off with them lol, hopefully everything will be resolved with the new set when they arrive

 

[roman726]

So I installed them in this position and so far seems to be working fine, is this the correct setup for them? looking at the back it would be 1st bottom then the 2nd from bottom to top. Thanks for any help I'm at lost and would like to get it all fixed up by trying everything before I send them away.

 

[roman726]

Here's a small update, OWC emailed me and told me they tested the RAM sticks and found no problems with them but were going to send me a new set. I really hope that's the issue with my iMac if not I'm afraid the logic board might be bad which it really bothers me knowing how little I have done with it. Oh well we'll see how it goes when I receive them.
Anyone know of any reputable places I could acquire a logic board if it comes to that? Thanks

 

[roman726]

Another update and this time writing from the iMac, I just received the new RAM sticks from OWC and installed them as usual and everything seems to be working just fine in the correct configuration as the OEM sticks. Thanks for helping out and giving ideas as to what to do.