Question no display after changing the BIOS

[ddanielkats]

After a one week break I couldn't turn on my pc. After I checked for solutions online I found about the CMOS battery on the motherboard and decided to replace it. Then my pc turned on and everything worked fine but a little slow it happened because CMOS battery was old and Voltage dropped to around 1Volt and it resetted my BIOS settings. so i got in to the BIOS settings and changed the profile to XMP (dunno why i did it) and enabled fastboot. After that , I couldn't get my display to show anything but the computer himself does turn on and the fans and leds are working.I tried resetting the BIOS by the jumper and by pulling the CMOS battery out and waiting for a long time and it didn't work , please help.


motherboard- ASUS Z97-A

 

[rgd1101]

full system spec? include make and model of the psu

 

[ddanielkats]

system spec? include make a

SPEC:
GPU- gtx 980 ti
CPU- i7- 4790k
motherboard- ASUS Z97-A
RAM - corsair vengeance lp 4gb ddr3 1600mhz x4
Power supply - Seasonic 850w (tested the voltages with a multimeter, seems good)

current status:
- Only one Ram stick is connected as i tried to test if the ram is faulty one by one.
-GPU is disconnected

-CPU and DRAM leds are blinking on the motherboard one after another.
CPU LED -> DRAM LED -> 2 sec break -> CPU LED -> DRAM LED -> 2 sec break

This issue has started after i've changed the BIOS to XMP mode and enabled Fastboot option, so i tried to reset the BIOS with every possible way, nothing solved the issue.

so far I've tried the things below:
-used MEMOK on the motherboard
-tried to reset the CMTS settings by removing the battery
-tried to reset CMTS settings with the jumper according to motherboard manual
-tested the RAM
-tested the connections from the power supply to the MotherBoard and validated that they are inserted properly
-Disconnected the power and reset button from the MotherBoard to check if any of them is faulty.
-also tried disconnecting the HardDrives from the Motherboard to eliminate the issue.
-changed BIOS battery to a new one

Non of above didn't solve the issue.
anything else I can try?