Thank you Edhawk,
I am using an iMac 2019 and you are, of course, correct about the adapter which I have ordered style shown below. I am trusting that the PCIe 3.0 SX8600 will connect firmly in this adapter to maintain rigidity. The ADATA uses an SM2262EN controller which I trust is iMac compatible, (I found no negatives). The ADATA SSD has chips on both sides so the usual long Sintech adapter cannot be used. I shall see how I go regarding fit. Screw cutout position matching the screw post is the unknown element depending upon the combined length of adapter and drive.
Regarding compatibility, I intend to preload firmware via an external drive case, fit the NVME in the iMac and then upload Mac os Ventura, I am aware some people recommend preloading the o/s on the drive while fitted in an external case. Arguably this may make the drive identification easier for iMac.
As the SX8600 is fairly new, comments about ease of loading, compatibility of firmware and actual performance in practice would be welcome. From the current information I have gleaned, there are not many drives which are trouble free in adapting to iMac. Samsung Evo Plus is to be avoided. The WD Black SN750, Sabrent Rocket and Intel 670p qualify for iMac compatible according to the many threads I have read. However high price and desire for TLC led me to the Adata which is currently good value according to benchmark speeds and price. In fact it sells for almost the same price as the Intel 670p which is QLC 700TBW, yet gives long life (1200 TBW) and speed equal to WD or Samsung - and without the high thermals and poor customer support accorded to the Sabrent Rocket.
Therefore in terms of user experience, I would value comments by anyone using the Adata SX8200, the SX8600 predecessor, or Adata drive performance such as thermals, rate of speed decay over time and reliability in general.
Many Thanks.
