i recommend u stay in hiveos or try another mining OS
but the problem u were having was related to page file most likely
for 12 gpus in windows u would prolly need close to 100GB of page file

i also kinda agree with the one dude about separating
i dont like having rigs above 4 GPUs a lot of times now
i have noticed a major uptime tick switching some of my problem rigs to 4 gpus
i have rigs that run for over a month without restart and without problems