Hi, I have a TX650m PSU and I'm planning on getting two Asus GTX 970's strix since both of these Video cards have a single 8pin power connector could I use this PSU to power these? I have a Asus Gene, 4670k 4.5g oc 8gb memory and a GTX 770 2gb.
I tried to do a little research for you on this but I wasn't able to find anything concrete. It looks like each card needs 28amps on the 12v rail, and your PSU is rated for 54amps on the 12v rail. In other words you would come up a few amps short. So in theory it should not work. But Asus's version of the card may have slightly lower requirements. So it may work for you, but most likely you would be loading your PSU more than I'd be comfortable with when gaming. It would probably be best to upgrade the PSU while you are at it. Just my opinion. Please if anyone else finds better info post it.
Should be fine champ as long as you aren't pushing a heap of extra voltage with your overclocking. Just read reviews of 970's in sli and you'll see for yourself - in most benching etc their test systems hover around the <500w load mark (eg this one). If you turn on adaptive v-sync consumption and psu strain will drop a fair bit.
To above post ~ 28 amps is taking into account an entire system with overhead for a plethora of variables - cpu/mb config, psu quality, avg amount of hdds etc.
You should be fine long as you are not going to overclock them. In the article I'll link it shows 970s in sli using 326 watts which is not bad. You have a solid psu so as it may be cutting it close you should be fine.
My best advise would be to forget the gtx970s in sli and the extra sli headaches here and there, just do a single gtx980 and that way you would have room for good overclocking and save some money. Unless you wanna run games at ultra settings 4k a gtx980 will handle anything 1080p/1440p especially if its overclocked. Also two gtx970s will add much more heat to your case than a single gtx980.
Whole Article - http://www.guru3d.com/articles-pages/geforce-gtx-970-sli-review,1.html
Power Consumption - http://www.guru3d.com/articles-pages/geforce-gtx-970-sli-review,4.html