If it were my $200, I'd buy a 1650 Super instead; they consume less power and run a bit cooler for less money than the 5500 XT, but based on your current hardware, it looks like you prefer AMD.
They both have relatively similar power draw. Reviews typically indicate that the 1650 SUPER draws around 100 watts under a gaming load, while the 5500 XT draws around 115 watts or so, probably nothing worth basing a buying decision around. Both cards should be roughly comparable to a 7770 in terms of power draw. Likewise, the temperatures they run at should depend primarily on what sort of cooler a given model is fitted with more than anything.
However, there is one reason I might shy away from the 4GB 5500 XT for this system. The card uses a PCIe 4.0 x8 interface, whereas other cards on the market today use a 3.0 or 4.0 x16 interface. The x8 interface should be fine on a PCIe 4.0 motherboard, as each lane provides double the bandwidth, making it similar to 3.0 x16, like the 1650 SUPER is using. However, on a 3.0 board (which most newer gaming systems have today) that falls back to a 3.0 x8 connection, and that has been shown to have some effect on performance, particularly in demanding games that fill the card's 4GB of VRAM. In many games there will be no performance hit, but in others, there can be a reduction of 10% or more. And since this FX system only has PCIe 2.0, that performance hit could be larger still. So, the 1650 SUPER will likely perform better in cases where the VRAM gets filled. Or the 8GB 5500 XT, though that card's not price all that attractively in my opinion, since you can often find some models of 1660 cards for around that price, and are generally faster.