Question PC upgrading and compatibility

[Zak]

Hello Guys, I m lookin' for some good advice regarding upgrading my PC. Currently, I have i7 3770, with GTX 660ti and 8GB RAM (2x4gb DDR3 1600hz). Motherboard -P8Z77-v LX2 .
I m planning to get used GTX 1070 (msi or zotac 8gb mini) or new Zotac GTX 1660. also I want to add 1x4gb RAM (for one of 2 remaining slots) and make it 12gb. PSU is 550w cooler master thunder.
What do you think, is this configuration going to work and which GPU should I go for?

Thank you in advance

 

[Boon72]

budget depending, i would get 2 x 4gb ddr3 and use all 4 slots ( around £32-£38)
Whilst the 1070 is a better card on paper over a 1660, the Ti an super are closer and would benefit from being the newer cards

 

[Zak]

Thanx for your response, and yes, I ve already bought 2x4 ddr3 coz 1x4gb wouldnt make significant difference. But I m still makin' up my mind about GPU. PSU has 2x6pin connectors, I hope it won't be an issue to use 8pin adapter no matter which GPU I ll get, 1660 or 1070