You need a
PSU adapter, swap to an ATX PSU and slap a 1080ti or Vega64 in there.
Thanx to all for the helpful input....i have now confirmed with the refurbisher from Amazon that my system indeed has only the 280 watt psu ...it looks like some of these 'tech' guys are not very knowledgeable....they messed up, and offered me a 100% refund (ups shipping paid) , or a (laughable) $20 dollar refundable discount....Despite the whole process leaving a sour aftertaste, this computer still has fairly good specs aside from psu (i7-6700, 32 gb ddr4 (not so important - for gaming), 500 gb ssd, optical drive)...so I'm debating whether to keep it or not...($430 cdn) i still have a spare good atx 460 watt enermax psu from the old Gateway p4 i believe was used a year or so - it still has that new electronic smell to it. (Tested it with dvm and paperclip)...but I'm unsure how trustworthy those 20 to 6 pin adapters are (and have never done that mod)...is that one referenced to ebay for $10 cdn dependable?...if i keep computer and don't swap the psus, but keep the 280 in there, can the psu handle a gtx 1650 (no external power cable i assume) given i don't add any more hardware, aside from plugging in the usb tethered mobile phone and the odd external western digital 'my passport ' 1 tb hard drive? The one odd thing with it is the rather slow usb data transfer...my Vista laptop and XP dell optiplex gx270 (recapped mobo) have about 10x faster speed (maybe windows 10 too bloated or i had antivirus defaulted to autoscan with usb detect)...Thanx for all suggestions.