Tricky Situation with Desktop Hp Pavillion 550 225ng regarding Graphic Card Upgrade

[JohnDoe15]

I have an Hp Pavillion 550 225ng, for specs please refer to: https://support.hp.com/lv-en/document/c05143850

All specs are perfect for me except for the gtx 960 2gb. I really want to get a better gpu but 300 watt power supply has limited me big time. After looking at the specs document and opening up my PC's case I found out that this GTX 960 is not a normal gtx 960 but a special one designed by hp(please see the specs document to see a picture of it). According to hp, the max power consumption of this specific gtx 960 is <120watt max. This pc has been running fine since 6 years with this card which proves that this 300watt power supply is strong enough to handle it.(Otherwise why would hp put a gtx 960 with this power supply). Considering this, I did my research about the graphic cards that should be okay with this psu. I only found two GPU's which should be fully safe, gtx 1650 which consumes 85watt max and gtx 1650 super which consumes 100 watt max. These cards should consume even lower than this gtx 960 which according to hp,  consumes about 120 watt max.  If 1650 super was easily availaible in Germany I would have went for it in a heartbeat but it is rarely found and even if there is one, it is hugely overpriced. Considering that, I thought about gtx 1650 which is perfect is terms of power consumption but not really a huge upgrade from 960. Surprisingly I found very reasonable prices for gtx 1660 super but it takes slighly more than 960 consuming 125 watt max. Also, it is worth mentioning that the recommended power supply for gtx 1650 is 300 watt, 350 watt for 1650 super and 400 watt for 1660 super. The recommended power supply for a normal gtx 960 is also 400 watt, but I am not sure about this specific gtx 960 which was built by hp. Considering that, the total power consumption of 1660 super is only five watts more than 960, is it still too big a risk to go with 1660 super? Or if it is too risky, do I have an option to upgrade my power supply? Would any normal power supply work with this PC or I will have to look for an Hp one? Do I also have very limited power supply upgrade options? If I add another 8gb of RAM how much more power would it consume? Would it be a good idea to remove my cd rom which is of no use to me to save some power? 

The specs

i7 6700

8gb ddr3

gtx 960 2gb

1tb sata hard drive 7200rpm

128gb sata ssd

hp 300 watt psu bronze

cd/dvd rom

memory card reader

wifi

bluetooth