Old Motherboard GTX 660 Problem

[bubuie]

Hey guys what's up?
So here is the issue i am having at the moment , I have an old PC that i want to give to my little brother, this PC has
M/B : GA-945PL-S3P
RAM: 2GB ddr2
GPU : GT 640
PSU : 650 W Deepcool ( added new one)

So problem persists in the case when i switch GT 640 ( this one does not require power supply) and put GTX 660 TwinFroze III OC 2 GB ( that has 6 Pin connector) when i plug this to my Monitor using HDMI Cable i get a blank screen, even can't see the BIOS , just black screen, updated the BIOS using @bios, But could not update from Q-flash in BIOS because it only sees the Floppy (who uses floppy now , and USB Drive is not recognized in Q-FLASH) , but the problem still exists, what can be the issue here?
Old GT 640 also was connected with HDMI to Monitor, but works, however when i plug this GPU it goes Blank, i know 1000% that this GPU works because i have tested on my main PC

 

[MyTechAddiction]

usually when a gpu has extra power connectors it will not start without them.Plug in the necessary connector.

edit :and stop fashing video card bioses.

 

[droopyRO]

I had a similar problem https://www.techpowerup.com/forums/threads/gtx660-pcie-x16-incompatible.242970/#post-3823271
Downgrading the motherboard BIOS was the solution.

 

[eidairaman1]

Sometimes if a card is not fully and squarely inserted it can cause this. Typically to verify the card works is to breadboard the rig, other solution is from @droopyRO