iMac 27" 5k 2019 Sticky cursor after change of blade ssd

[Pixelspy]

Hi Mac pro's. Sorry for my bad english i am german living in Andalucia.
My problem is the following. I bought a 2019 27" 5k iMac. It came with a 512GB blade SSD and no further HD/SSD. I upgraded it with a Crucial P3 Plus 4TB M.2 PCIe Gen4 NVMe SSD that i connected with an adapter that i successfully used already in various MacBook Pros. Added an 8TB Seagate Barracuda with a spare connector-cable. So far all fine. Mac powers up, both drives are recognized by the system, was able to format them, installed Sonoma and thought all is fine now with the tuned iMac. Then i remarked, that the cursor is somehow sticky. When you move the mouse / trackpad it takes a second to get it moved, also when you move it and stop ( to for example click a folder) it makes a little jump. I tried everything. Installed new system, downgraded (fresh install) to Monterey...no change. Tried a keyboard and mouse with USB cable...same issue... Of course tried resets of NVRAM / PRAM. Looked after the TRIM activation on the Crucial SSD which is on... Bought an expensive external housing for the original blade SSD, the Mac came with, plugged it in an external USB-C port, started from it and the problem was gone. Starting from the internal SSD again brings the problem back. No idea what to do now... Can anybody help me please???? Thank's in advance... Franc

 

[Bigwaff]

Bought an expensive external housing for the original blade SSD, the Mac came with, plugged it in an external USB-C port, started from it and the problem was gone. Starting from the internal SSD again brings the problem back. No idea what to do now... Can anybody help me please????

What version of macOS is installed on the original blade SSD and which version is installed on the internal SSD?

 

[Rich B22]

I converted a 2017 27" iMac Fusion drive with a blade SSD, using an adapter meant for a 2015 Macbook along with a second SATA SSD where the hard drive would go and it works fine. I'm not sure, but it is my understanding that not all iMac's will work with an adapter, so that may be the problem, unless wither the adapter or new SSD is bad. Weird that everything else works other than the cursor, though.
If you can't sort it out otherwise, I'd suggest putting back the original drive in the blade position and putting your new drive in an NVME to SATA case in the hard drive position. Alternatively, just put the new drive in your new expensive external case and use it that way. Boot from the internal and move your User or it's folders to the external
Good luck

 

[Pixelspy]

What version of macOS is installed on the original blade SSD and which version is installed on the internal SSD?

Hi Bigwaff, both were / are Sonoma 14.3.1

 

[Bigwaff]

When you move the mouse / trackpad

Is it an Apple mouse or a trackpad? If so, the version w/ replaceable batteries or the version with rechargeable internal battery?

 

[Pixelspy]

Yes, Apple, the one with internal battery. Tried the one with replacable batteries too. Same same...