Hi - this is my first post so would really appreciate some advice on my problem.
I have an Asus M5A99X EVO motherboard with a Radeon sapphire 5450. Running windows 7 64 bit.
I have been trying to change the Sapphire to a EVGA Geforce GTX 750 Ti single fan card.
I have updated the motherboard BIOS to the latest version.
I removed the Sapphire card and installed the 750Ti and connected it to an Asus PB287Q monitor by HDMI.
This is the problem:
When I switch on the computer I cannot get past the initial ASUS "welcome" screen where it says "press DEL to enter set up". And nothing happens if I press DEL. On the asus motherboard the Boot device LED continues to show constant red.
 
This also happens with my Dell monitor.
 
I have scoured all the on-line advice but have found nothing that helps so far.
Any help would be gratefully received.
Thanks in advance.

A standard SATA3 SSD drive connected to SATA6G terminal number 1 on the Asus M5A99X EVO motherboard.
8GB ram
Radeon sapphire 5700 (not 5450)
AMD Athlon II X3 460 3.40GHz
 
All the above has worked OK for some years.
 
Problem is changing the graphics card to 750 Ti - cannot get past the BIOS Post screen - Boot device LED is constant red but monitor can receive signals from both HDMI and/or Display Port cables.
 
Even tried clean install of windows onto new SSD but cannot get past BIOS post.

Looks like one of the early generation UEFI bios boards. As much as I keep hearing that Maxwell doesn't work on non-UEFI boards (they do, just not always), most of the problems I've seen were on mobos that do have UEFI, but are first generation boards.
 
Reinstall your old Radeon and do the following:
1) Ensure that you have the latest bios update for your motherboard.
2) Go into bios and see if there's a way to change PCI-E from "UEFI" to "Legacy." If yes, do it.
3) Reinstall the 750 ti and report back.
 
If you still have no luck, try to return your card and get the MSI 750 ti. This one here: http://www.amazon.com/MSI-OC-PCI-Express-N750TI-2GD5/dp/B00I6DLIB8/ref=sr_1_1?ie=UTF8&qid=1441087791&sr=8-1&keywords=msi+gtx+750+ti
 
It has a physical switch on the card itself that allows you to switch to a bios (on the card) that works for motherboards with this issue.
 
Best of luck!

i will spare you the story behind why i'm suggesting this, but if you have another type of monitor cable besides hdmi, try using that connection to the video card and see if it does the trick. worked for me once. cheap and easy enough to try if you have the cable.