what happens when you mine with just 1 card,
then try mining with just card 2 ,
then try mining with just card 3
then try mining with just card 4

What are the hashrates?

IF they are all ok but when you mine them all at the same time you need a WATT monitor plugged into your kettle lead

like this https://ae01.alicdn.com/kf/HTB1I64nKFXXXXbaXpXXq6xXFXXXn/2013-New-EU-Power-Meter-Watt-Voltage-Amp-Energy-Monitor-Analyzer-LCD-display-5pcs-lot.jpg

IF The one card still has issues, replace the risers, reinstall drivers, try again
if you still have issues try the card in another PC (it may be faulty)

if its ok in the PC again try the WATT monitor, your PSU may be using above its threshold.


basic torubleshooting here.