5700xt odd issues

[JaseDays]

Ok sorry this a long one.  I purchased a new 5700xt (literally the only MSRP card available)  for my son for Christmas.  Since then we have had crashes, freezes etc on his machine.  But here is the kicker, when I put the card in my machine it works fine.  No crashes, nothing.

 

what I have tried

• ddu and probably 5 different driver versions
• Replaced with new psu
• underclocked card - watt man
• undervolted card - watt man 
• adding small amounts of voltage to ram 
• decreasing ram speed 
• setting all fans to 100 (although no temp issues)
• previous card rx580 had zero issues
• tries putting two separate psu leads to card (instead of Y splitter)

 

he has an asus b450 board and 2600x

 

im at a loss....