what power supply with gtx 970 /980 ?

The quality is more important than the actual output. A good quality 500w one would be ok for that rig for instance BUT that said if buying new I see little point in going less than 650w. (650w should cover you for all bit theost outrageous GPU unless you want to go sli or crossfire).

Don't skimp maybe this will help. Expect to pay £60-£80 ($70 -90)

https://www.techradar.com/uk/news/best-pc-power-supply

Corsair HX or RX 750 would be my first choice. Excellent brand, gives you more power for furure expansion, silent and 80+ certified. You can’t do better. 

Digikid1 said:

Corsair HX or RX 750 would be my first choice. Excellent brand, gives you more power for furure expansion, silent and 80+ certified. You can’t do better. 

I can vouch for the Corsair power supplies.  I have an HX850 80+ that I've been running for about 5 years.  Flawless during that time and it will deliver more than enough power over its lifetime to my system.  I've never skimped on power supplies, it's just not worth it.  Get a good powerful one and you'll never have to think about it again.

Digikid1 said:

Corsair HX or RX 750 would be my first choice. Excellent brand, gives you more power for furure expansion, silent and 80+ certified. You can’t do better. 

Actually he could do a lot better.
EVGA G3 750W for $90 currently on Amazon, vs $120 for the Corsair.
Plus, Corsair's customer service can't shine a light on EVGA - I've had so many bad experiences with Corsair>
EVGA will got he extra mile, Corsair will make you feel like you had to walk an extra 10 miles to get things resolved - and this is feedback from numerous friends.
Of course everyone has opinions, but if you compare the EVGA and Corsair HX750 on amazon, the EVGA has almost 30% more customer reviews (4300) at an average of 4.5 out of 5 versus the Corsair's 3200 reviews at 4.3 out of 5 average review score.
Numbers don't lie, at least not when you get into that kind of review volume.
Not saying the Corsair isn't good, but it's statistically not the best option and more money.
Don't be fooled by the technical marketing verbiage. Look at warranty and customer service history.
Both have 10 years.

https://www.amazon.com/EVGA-Supernova-Modular-Warranty-220-G3-0750-X1/dp/B005BE058W/ref=pd_lpo_vtph_147_bs_tr_t_1?_encoding=UTF8&psc=1&refRID=N6X9VGQQJ10Z1XGW36Q3

Rob_In_Phoenix said:

Digikid1 said:

Corsair HX or RX 750 would be my first choice. Excellent brand, gives you more power for furure expansion, silent and 80+ certified. You can’t do better. 

I can vouch for the Corsair power supplies.  I have an HX850 80+ that I've been running for about 5 years.  Flawless during that time and it will deliver more than enough power over its lifetime to my system.  I've never skimped on power supplies, it's just not worth it.  Get a good powerful one and you'll never have to think about it again.

That's what I just upgraded to. :)  Seems like a nice PSU.  My first modular one.  I was tempted to get the HX850i which I guess has some app to tell you the actual power usage.  But none were in stock. :(

I also highly recommend EVGA power supplies, I got myself a 750W G2 a couple of years ago.

Yeah, EVGA is pretty solid.

ok thank you , yes EVGA  good brand but unfortunetely mine had a problem  , no lucky
 but now my rift is sold ... my graphic card burnst et one of my HD ( 2 TO...photos, job, ...) falled because i often moved the PC tower . I will wait a little
maybe the Quest
thanks everyone