Functioning GPU not working in functioning computer

[Ignuus66]

I'm putting together a SFF used computer for a friend, and I managed to get a used GTX 745 for a pretty cheap price.
The computer I'm putting it in had a GT 210 with which it works perfectly, but is insufficient for her needs. (The comp is a Lenovo m90 with a i3-540). The GTX 745 I got works perfectly well when I put it in my computer, with it running benchmarks as I expected without any crashing or freezes.
The lenovo in question also works perfectly when I put the GT 210 in it (Win 10 installed).

But when I put the GTX 745 in, all that happens is the motherboard beeping 5 times, which, according to lenovo's troubleshooting page, means that something is wrong with the display.
(I followed everything they recommended on the troubleshooting page, to no avail)

Anyone have any ideas?

 

[basroil]

Update the bios and try again. Hopefully it's just that and a workable bios revision is out there

 

[Ignuus66]

Update the bios and try again. Hopefully it's just that and a workable bios revision is out there

I tried it, it didn't solve the problem, though now atleast the Bios is at the latest version.

 

[basroil]

I tried it, it didn't solve the problem, though now atleast the Bios is at the latest version.

In that case it's a motherboard incompatibility or power supply issue, neither of which can be solved without spending more than the computer is worth