Cannot get into BIOS settings

[Kwerty]

As the title says, I can't get into my PC's BIOS settings.

After changing my CPU's fan to an aftermarket one I haven't been able to get into windows. It just says this.

So I've obviously tried to go into the settings by pressing delete on this screen, that just brings me to this screen that has the same error as before. The only button that works on that screen is the alt-F2 to get into the EZ Flash.

At first I thought my KB wasn't working, but if I can get to the EZ Flash menu then I guess it is...

What I've tried:

• Reset CMOS by removing the battery
• Reset CMOS by changing the jumpers
• Flashing a newer BIOS version via EZ Flash
• Removed the cable that connects the case's front USB (as suggested a couple of times on Tom's Hardware forum)

PC specs:
AMD Phenom II X6
M4A88TD-M EVO
4GB Corsair 1600Mhz RAM
Sapphire HD6870
Antec True Power v2 480w PSU

I've googled the s**t of out this and I haven't found any solutions. Any ideas would be great.

Thanks

 

[NomNom]

Make sure all USB devices and cables are disconnected, switch on your Pc and see if you have the same problem.

Otherwise have you tried going back to your old CPU fan?

 

[Kwerty]

Ya when I don't have anything plugged in I get a "No keyboard detected" warning on top of the one I'm currently getting.

No, I haven't tried going back yet. Right now I'm doing the battery / jumper thing again. Will try after that.

EDIT:

No difference when using the stock cooler.

 

[sajunky]

Do you still have overload message if all USB ports are empty?
Try different keyboard and without mouse. Repeat reseting CMOS, but disconnect power cord first.

 

[Kwerty]

Do you still have overload message if all USB ports are empty?
Try different keyboard and without mouse. Repeat reseting CMOS, but disconnect power cord first.

Yes, done and done. No difference

 

[sajunky]

Does a new cooler have the same type of header (3-pin/4-pin)? Thinking of damaging power supply. You also need multimeter to check power supply voltages.
Other typical problems are not changing thermal paste when replacing cooler, pulling out CPU from the socket when removing old one and not locking a cooler properly on the CPU giving poor contact with CPU.
Now when you put back a stock cooler, does it rotate as usual?

 

[Kwerty]

Does a new cooler have the same type of header (3-pin/4-pin)? Thinking of damaging power supply. You also need multimeter to check power supply voltages.
Other typical problems are not changing thermal paste when replacing cooler, pulling out CPU from the socket when removing old one and not locking a cooler properly on the CPU giving poor contact with CPU.
Now when you put back a stock cooler, does it rotate as usual?

Yes it's the same. I don't have a multimeter to check unfortunately.

I did actually change the thermal paste before deciding to go for a new cooler alltogether. When I then took the old cooler with the new paste off it did come out of the socket without me releasing the clip. I didn't think anything of it at the time but I guess that could've been pretty bad. After that I did in fact not lock it properly and the PC didn't POST. I then went back and pushed it in properly. Since then it's been giving me this error with both coolers properly attached.

I'm going to do a bench test now (sigh.) to see if something might be shorting somewhere. Will report back then. Thanks for the help thus far

EDIT: Problem persists.

Should I start looking for a new CPU / Mobo?

 

[sajunky]

I don't know. Pulling out CPU is not critical, it happened to me many times, sometimes heatsink don't want to reparate from CPU. CPU handling is very different story, touching pins with fingers can do permanent damage due to static electricity. Check CPU (or LGA socket) for bent pins.

Maybe you need to take it to a shop for checking.