All of my motherboard's PCI Express 3.0 x16 slots stopped working

[bavor]

Yesterday afternoon both PCI Express slots on my motherboard stopped working. In the "BIOS" nothing plugged into the slots is detectable. It shows up as an empty slot in the BIOS no matter what graphics card I put in them. Windows does not detect any GPU other than the Intel HD Graphics 4000. Nothing was changed in my hardware of BIOS settings recently. The on board hardware(LAN, sound card, USB 2.0 ports, USB 3.0 ports, SATA ports) works fine. I tried an old USR 56K PCI modem I had laying around in a box in a PCI slot and it was detected by the BIOS and the correct drivers were automatically installed by windows.

System Specs:
i7 3770K overclocked to 4.4 GHz and water cooled.
Asrock Z77 Extreme4 motherboard with the latest BIOS available for the board.
EVGA GTX 960 FTW
32 GB RAM (8GB x 4 sticks) Kingston Hyper X DDR3-1600
1 TB Samsung EVO 850 SSD
4 TB HGST 7200 RPM hard drive
SeaSonic S12 650 Watt power supply (SS-650HT)
Windows 10 Pro

I tried the clear CMOS procedure per the manual and restoring the CPU to stock speed, and that didn't fix the issue.
I tried removing or disconnecting everything except the CPU and RAM and that didn't fix the issue.
I tried the clear CMOS procedure again and that didn't fix the issue.
I tried a GTX 750 ti(that uses the power of the slot and not external power supply power) in both slots and that didn't fix the issue.
I tried my old GTX 660 ti in both slots and that didn't fix the issue.
I tried the clear CMOS procedure again after trying the different graphics cards and that didn't fix the issue.
I tried the GTX 750 ti again and it showed up in the BIOS, but not in windows. Upon rebooting, it was gone from the BIOS.
I tried the clear CMOS procedure again with the GTX 750 ti installed and that didn't fix the issue.
I tried disconnecting everything(speakers, extra USB stuff, 7200 RPM storage drive, webcam, microphone, etc..) again except the GTX 750 ti, CPU, SSD, and memory, clearing the CMOS and that didn't fix the issue.
All of the graphics cards that don't work in my current desktop work in my old socket 775 desktop.

At this point, am I to assume the PCI Express slots on the motherboard are dead for some reason or is there more troubleshooting I can try?

Finding another Z77 chip set motherboard these days is a bit difficult. I wasn't planning to upgrade for a while. I did find a few Z77 chip set motherboards for sale, but many of them are in the $150-$300 price range.

 

[ohenryy]

Maybe some power lanes on the PCIe 16 are damaged and does not power enough the GPU for detection?

 

[carlo_bigtunes]

open cpu socket check for pin , there's a bent pin or broken. if it ok then try with different cpu. still have a problem then pls flash new bios file from asrcok website.

 

[bavor]

open cpu socket check for pin , there's a bent pin or broken. if it ok then try with different cpu. still have a problem then pls flash new bios file from asrcok website.

I already checked the CPU socket for bent pins this morning and didn't see any. I don't own another CPU of the same socket type.

As I stated above, "with the latest BIOS available for the board." I have the latest BIOS which is several years old at this point.

If diagnosing this issue requires buying another CPU, then I might be better off just upgrading to a new motherboard and processor.

 

[bavor]

I have no idea what changed, but all of a sudden I can get the BIOS to detect the graphics cards again and they work in Windows. I tried multiple times disconnecting everything and booting whit just the CPU, RAM, SSD, and GPU and all of a sudden the graphics card was detected.

Now if this is going to be an ongoing intermittent problem, maybe I should replace the motherboard and processor now.

 

[carlo_bigtunes]

pciex detected from cpu , maybe motherboard pin cpu socket not connected properly / loose.

 

[bavor]

pciex detected from cpu , maybe motherboard pin cpu socket not connected properly / loose.

I can't see any bent pins when looking at the socket with a magnifying glass from several different directions and the CPU doesn't move at all when the latch is closed for the socket. The socket itself doesn't move either.