Upgraded GTX660 to GTX1070, now Lenovo K430 won't boot

Hello All,
I've been trying to upgrade my Lenovo K430 from a EVGA Nvidia GTX 660 (not stock) to a EVGA Nvidia GTX 1070. The system operates fine, I just want to upgrade my performance.
Current specs:
Win 7 64 bit Pro
24 GBs RAM
Intel i7 3770
CIZ75M Motherboard (stock lenovo)
Thermaltake Smart 650w PSU

When I put in the new gpu, the screen shows the Lenovo title screen and the gpu fans spin for a second, and then it stops. The system then has 3 spaced out beeps and the screen goes black. The Hard drive will spin up for a split second the the bootup never begins.

PS. I have narrowed it down to a BIOS/MOBO issue. Lenovo hasn't supported this platform since 2012 and is unflashable (Lenovo Says). Would upgrading to WIN8.1/WIN10 fix this problem is the GPU too new for my out-of-date (4yrs old) system. Please Help..........

try and disable secure boot.

Assuming that you've checked the obvious like power to the gpu etc ??? However if your bios is un-upgradable you may be sh!t out of luck. I had this issue with my R9 290 and old motherboard that hadn't been updated to a UEFI bios. Luckily for me there was a newer bios that fixed the issue, once the newer bios was flashed the motherboard would boot with the new card.

look in the mortherboard manual, it will tell you what boot beeps mean

When i googled 3 beeps i got a few different results, but depending on how easy it is i would try the 1070 in a different pc to make sure its not faulty. But ive run newish cards like the 960 on hardware as old as that with no issues before. If you have a spare hdd try doing an install of windows 10 on to it just to try.