Short circuit issues when dual mine ?

I have six gpu mining rig. 4x r9 390 , 1x Rx 470 4gb,1x Rx 470 8gb. I have 2 psu 1000w gold + 750w bronze connected using Add2psu . 1000w psu powering motherboard, CPU, ssd, 2 r9 390 , 1 Rx 470 4gb. 750w psu powering 2 r9 390, 1 Rx 470 8gb. I modded 470s , 4gb produces 28 mhs 8gb produce 27 mhs. I orderclock r9 390 and undervolted slightly -20mV. On average I consume 1500w, if temp is hot, it sometime reaches close to 1600w. My 2nd psu typically consumes 630w. max reached is around 680w. In total my hash rate was 180mhs.

Yesterday I thought of turning on dual miner in claymore to mine sia. Once I turned on ,it run about 5 mins and my killawatt meter died. Then I tried connecting directly to my power connector.similarly after 5 mins my fuse went off. Without killawatt I couldnt find the total watt consumed after turning on dual miner. One thing I noticed strange about dual miner , I got around 168mhs instead of typical 180mhs, my rx470 4gb is running at 20mhs instead of 28mhs .also this gpu is where my monitor is connected. Not sure why I got low hash in it.

I jst ordered a surge protector power strip now. Usually how much spike in power is expected when dual mine ? Also why my fuse goes off ? Also is there any configuration changes I can make like connecting more gpu to psu or anything I can make use of ? Thanks.