It definitely is a space heater now, before with my strix 2080 the glass was cool to the touch when gaming. I have have grazed my leg against it plenty of times now with the RX580 I actively make sure my legs doesn't touch the same window in the same case that has been there since 2017(first time I grazed it with the 580 in there I panicked and took the gpu cooler off to regrease.. no improvement). While its not scientific cool to the touch vs feeling like you are being trained not to touch it is not something I need numbers on.
Oh, there's no oc on this thing at all, not willing to bring more heat to the card. Card progression Asus 1080ti turbo converted to g12 with 240 aio, zotac 2080ti in Oct of 18 and finally Asus 2080 strix since Nov of 18.
rubbish. Not a hope in hell that the 580 is heating up the air in your case enough to cause the glass panel in the side to get that hot.
But, let's for arguments sake say this actually happened, then the cooling inside your case is useless. In fact you must have no cooling and all the vents blocked up.
What RX 580 was it?