Hi,
Will give $50 worth of btc to anyone who can help me out. Assembled my 4 x 1070ti mining rig about 3 weeks ago has a 1200w corsair platinum psu, asus h270 plus mobo, 2 x 4g ddr4 ram, running windows 10

So my first problem is when i benchmark each singular gpu on its own i get good hashrates, about 460 m/hs on equihash. But when i run more then one gpu the hashrate of the others drops significantly. When i try run all 4 together i get like 720 m/hs which is trash for all 4 gpus. I have tried uninstalling and reinstalling the latest drivers for my gpus and a clean install of windows. Does anyone have any tips for this?

My second problem is with all 4 gpus running any mining software i use crashes after a few minutes of mining and just freezes my pc. I tried getting 4g more of ram to bump up my system to 8gb (improved overall stability but still get crashes). I really am stumped here and have no idea what to do with this one, have tried searching through forums but no solution has helped. Thought it was a nicehash issue, then started using nemosminer and mining pool hub. Still crashes and shit hashrates...

So, i think this may be an issue with faulty hardware. My 2 guesses are either my powersupply or my motherboard. I am guessing one of them cant support to provide enough power across the rig with more then 1 gpu. It cant be my gpus because when i plug each in separately  and benchmark them they all give me good hashrates individually. Just not with more then 1 plugged in...

I have spent the past 3 weeks trying to solve this and its doing my head in, alot of lost revenue aswell so if any one has any ideas please let me know.

Thanks,