SSD not recognised

I've tried all the sata ports, I replaced the main BX200 drive with a cloned copy on the MX500 and no joy, I used the same cable I used on the BX200, as far as I understand this rules the cable and sata port out. The same thing happens if I use it has a spare storage drive..... it'll pop up in the disk drive window and then disappear, the first time I noted this oddity was in disk management the drive showed up and then disapeared.... are all sata cables are the same regarding data handling? When I get chance I'll disconnect all drive's and concentrate getting bios to see the drive, all my data is there on the cloned drive, as you say I need to sort this out. Dave

Dave, is your BIOS up to date?
Did you ask Crucial help?

Yes I'm flashed and using latest bios, yes I did contact Crucial but they haven't replied as yet so I will try again. I've just ordered some Sata III leads so they will be a day or so, I'll leave it until they arrive so we can be sure, I don't know what the present leads are or if they are 'bottle necking', they'er not marked so may well be 'cheapos'. Dave

The Molex connector has
Pin # Color Function
1 Yellow +12 V
2 Black Ground
3 Black Ground
4 Red +5 V
Molex connector - Wikipedia

The SATA connector also has a 3.3V (orange). Some SATA devices don't need the 3.3V but others do.
Serial ATA - Wikipedia
That is why it didn't work with the Molex to 2 Sata splitter.

Yes I am aware of the voltages and the colour coding.... I have to repeat myself here-: One power feed from the psu to a Molex to TWO sata plugs- both drives will work in ANY plug, please note: ANY plug but will not work when the TWO ARE connected - I'm sorry I can't make this any clear, the two drives have their power feed in parallel because I'm using a splitter connector. I will add, it is exactly the same with ANY drive, lets try again.... we have one Sata power lead connected to another Sata power lead...... FIW, both drives are exactly the same make, brand model - the lot and its exactly the same with ALL the drives that I have tried of various manufacture. If the leads are wrong in any shape or form the drives would not work. According to Crucial MX500 the only indication on the back of them is 5V at 1.7 Amps.... there's no servo requriing a 12V supply like HDD's for sure, lets stick to HDD and ssd here because NVMe drive's ARE different, I suspect all three voltages *could* 12, 5 & 3.3V come into play here and they all come from their respective rectifiers, filter capacitors and chokes. Dave

Calm down Dave, you're loosing your temper for very little.
Now you made it clear but it wasn't on your previous post.

BTW, the fact they are feed in parallel shouldn't make any difference. The PS is able to feed many drives.
As I wrote, the only explanation is the absence of 3.3V on the Molex connector.

Sorry if I gave the impression I was on a short fuse. What would be interesting would be to try the power leads from the DVD's.... but that would be a struggle because they are short and not that flexible and hardly any room to move. Something strange was happening because at first when I formatted and initialised the new drive it'd disappeared shortly after boot up.... but not when connected elsewhere - what fun that was. Sorry too I missed that 'little green thanks' at the bottom. The matter is solved and that was the reason, something I'd never seen before, I posted as it might just help someone else. Thanks again, Dave Edit: I still haven't heard from Crucial as yet.