Imac NVME SSD installation problems

[pawnhawk]

Hi All, First off I am new to Mac's well in my case imac. This is complicated so please bear with me while I try to explain my problem.
I bought my imac which is 27" 14.2 imac with 16Gb ram and a 3Tb standard HD, it was running great but I thought I would like to get a bit more speed out of it.
So I did alot of research to see what my options were, and decided on a NVME SSD which would fit on the motherboard of my 2013 imac.
So I ordered a Samsung evo 970 500Gb NVME SSD and a Sintech adapter, well that what it said on Amazon, but am having doubts about it now.
The adapter does not say sintech anywhere on it, it only says M2 NGFF os 2013 -2017 macbook SSD RoHS.
So as I had got it I thought here goes and give it a try. Took the imac apart and finally got to the motherboard, fitted the adapter and SSD ito it's slot, put it all back together.
Switched on and mojave started up great as before off the 3Tb HD, started up disk utiuls great there was the SSD, so I erased the SSD to apple format.
Inserted mojave installer into USB slot, started mojave installer great everything seemed to go OK, found SSD and the whole precess started. Now the fun begins the process of installing took 3 hours, I thought this does not seem to be right but let it go.
Once it finished and then restarted the imac great mojave started off the SSD, now the problems start, the dreaded fan was very loud, but before I installed the SSD fan controller I wanted to check temperature of CPU, all good was running between 30 - 40c, loaded SSD fan controller set to manual great fan went quiet. Loading software onto the SSD was extremely slow, far slower than the 3Tb HD.
Then starting the programs up was very very slow, the 3Tb HD was about 4 or 5 times faster than this SSD, so I thought I would do a speed test. Started up Black Magic and was getting just above 300Mb read and writes times, which I thought was not to bad, but why was it so slow. Did alot of research but could not find anything, except something to do with TRIM but when I looked it was on, so I was at a total loss.
I had a thought I had got and old 240Gb SSD, tested it and it was working OK, so did another strip down took out SSD and 3Tb HD, and replced it with the old 240Gb SSD, put it all together again.
Switched on and the dreaded ? on screen, back to the PC for some research, but just as I switched on the PC and waited for it to start, the apple logo appeared on the imac so I left it to do it's thing.
Soon enough the Disk Utils started, went into disk utils erased the SSD to apple format, went to install mac os and great the mojave installer started, it only took 30 - 40 minutes to complete.
Restarted the imac and it started very quickly, installed a few programs and they all stated about 10 times faster than the samsung EVO 970 SSD. So I did another speed test for this 240Gb SSD and it came out with just above 200Mb read and writes times, so why was this slower SSD far faster than the Samsung EVO 970 SSD, I am at a total loss and don't know what to try next, so I am hoping that some out there has had the same problem as me or who can point me in the right direction.
Thanks in advance for any help you may have.

Pawnhawk

 

[Cory Cooper]

Hello and welcome.

In short, the Sintech adapters are really made for the MacBook family and not iMacs. I would lean towards the Sintech adapter, and the fact that the iMac isn't natively compatible with NVMe M.2 flash storage.

C

 

[Harry Trent]

Cory could be right about the adapter being incompatible but I'm wondering if it could be a heat problem. The 970 Evo NVME series is among the fastest m.2 NVME drives out there but they run famously hot. Most people deploying the 970 evo find they need to put heat sinks on it and have good case ventilation to prevent throttling. All in one computers like the iMac have poor interior case ventilation.

In this scenario, you would be better served with an ordinary 2.5" SATA SSD. In real world computing you won't notice much difference between a good SATA SSD and an NVME drive and what difference there is shows up mostly in boot times.

 

[pawnhawk]

Thanks for your reply's, I think you may be right with the Samsung Evo running hot, but as I said at the moment it is out of the imac and in place is a 240Gb SSD, no other drive in the imac.
The imac is running really fast with this cheap 240Gb SSD, so I will probably just get a good SSD to replace the 3Tb HD that was in there in the first place.
I am waiting for an adapter to test the Sumsung Evo in a PC, this will make it easier to monitor and to see if there are heat problems.

 

[Harry Trent]

What bus will the 970 Evo NVME be using with the adapter when deployed in the PC? A SATA adapter will completely mitigate the performance advantage of an NVME drive. NVME is designed to use the PCI-e bus which has a much greater bandwidth than the SATA bus. They do make PCI-e adapters for motherboards without m.2 NVME sockets but you may not be able to use the 970 Evo as a boot drive in that case, at least on many older motherboards that did not ship with m.2 NVME socket technology. The bios may not recognize it as a boot option.

 

[chrispl0]

Doesn't the 3TB drive have a 125GB ssd with it anyway?

 

[pawnhawk]

The only reason I am buying this adapter is to test the M.2 SSD, as I cannot get it to work properly in the Imac.
If I return it and it is working they are not going to give me a full refund and now used SSD, so testing it first and if it is working, then I may sell it on ebay and just get a normal SSd to replace the 3 Tb drive and that would cure every thing.

The adapter is a PCIe but as I said I only want to test the M.2 SSD and it will accept the M.2 SSD.

The 3 Tb drive is just a standard HD from Seagate and not a fusion drive.

At the moment I am slowly giving up on the M.2 SSD idea, as keep tearing down the IMAC and I have done it 3 times now, eventually I think I may damage it, so I wll just go with the standard SSD.

Thanks to all that contributed.