Driver instability only when adding 3rd GPU

Hi all - new creating forums, that’s just how desperate i am!

TB250 biostar BTC+
2x GTX1080ti Gaming X
1x GTC1080ti armour OC
8gb Ram
1600 watt PSU
128 gb SSD
intel celeron
USB risers for all GPUS

been mining Z cash easily with 2 GPU’s (gaming x and armor OC) getting good results and running super stable mining z cash with ewbf 0.34b for about 2 months. problems came when i bought a third GPU (another Gaming X)

the 3rd card makes the entire rig super unstable, it is detected in geforce experience and device manager.
-when i open nicehash/ewbf my graphics drivers crash and recover but then my computer only registers 2 of the cards and then i am able to mine, usually graphics drivers crash then i get a windows prompt then nothing works(sometimes mines zcash for 15-30 seconds before crashing)
-sometime when i reboot it doesnt even detect all three GPU’s, it detects them when it wants to
-i can mine LBRY using all three cards and runs the miner well but is still feels unstable (havent ran for more than 10 minutes)

what ive tried:
-reinstalled the drivers a thousand times- done clean installs, done reinstalls, completely deleted and reinstalled all GPU software.
-moved cards around to different PCIe slots and with different rizers/slot combinations
-formatted the hard drive and did a complete reinstall/setup of the Rig’s software

haven’t tried:
-changing clock speeds - dont think power is the problem
-changing BIOS

?? When you move the card around, is that card the one that fails again or is that that slot / rizor?
Are you running stock or OC? If OC, did you set your benchmarks back to zero and start over (ever card, even the same type of card, are all different)?

Didn’t check which cards run on various slots - will test in morning and let you know!

They are all standard, just temp capped at 70C with msi afterburner

can you screenshot that and post it when you are able?

Give this linux mining pendrive a try

Disclosure: I am the publisher