Optiplex 7090 MT with Nvidia 4070

OK, a few things about the specs here. The RTX 4070 is rated 90W below the RTX 3070Ti and 15W below the RTX 2070 Super. Also AMD lists the 650W PSU based on a Ryzen 9 5900X which pulls 105W. While your i7-1170 pulls 65W. Depending on what other hardware you have in the system (pulling wattage) I suspect the 4070 will run properly especially since you already have an RTX 3070 running with no problems.  I was not clear on your post though, you do have an RTX 3090 running right now right?

You may have noticed both cards have 650w PSU recommended by Nvidia.  They're covering all the bases, like if somebody does their own custom build.

Dell's PSU's have more power on the 3.3v/5v per total watt than aftermarket PSU's.  So while aftermarket PSU's boast more total power, it takes having to buy a higher watt PSU to the same, if not more, power on the 3.3v/5v rails as Dell OEM's.

If an RTX 4070 is ran on a Dell OEM 500w PSU, that still leaves 300w for the PC and should be safe to run. I highly doubt it will trip the PSU.

You probably looked at the Nvidia site for wattages?  There's no indication of either card being tweaked by Dell.

And for those reading this, the RTX 3070 is on the 7090 spec sheet 

thank you so much for the response. yeah I just wasn't sure if I need to get the OEM 3070 that's on eBay. I was just wanting to make sure before I decided if I was going to go that route or get a brand new 4070 or even an a2000. 

I just have on board video for right now. I just wasn't sure if I should just get the OEM Dell 3070 because I wasn't sure if that's tweaked specifically for the motherboard. I bought the PC on eBay. I was even looking at the a2000s.

I really appreciate the response because I just can't find much information on my options and I just was confused because Nvidia's website says 650 watts power supply recommended. 

I need to learn more about the Dell PSUs. I didn't know that. even though they're rated at 500 watts, they're actually way more powerful

RTX A2000 = 70w.  Super safe on power consumption.

If you're deciding between 2 cards, can always Google something like "RTX 4070 vs. RTX A2000."

If you' like gaming or have other programs dependent on graphics cards, can also always Google system requirements.