AMD Athlon 64 3700 + at 800 Mhz?

[Mirinda]

hello to all
Here is my concern. I have a AMD Athlon 64 3700 + cpu Clawhammer ES, a motherboard ASRock Motherboard K8Upgrade-NF3 with a 1.5 bios.
Here's my concern:
I start after the post, the pc tells me it is a 800 Mhz.
Assistant windows, cpuz, OCCH tell me that it's a Clawhammer ES but a residual increase of 4 with a frequency of 200 so far 800 Mhz.
In the bios, when I bring a change, I have to restart the following message "bad checksum error press F2 to run setup or f1 to load default"
What can I do?
thank you in advance

[Dr. V]

The error that appears depends on the type of BIOS used. Any of these error conditions indicate that a Basic Input/Output System (BIOS) test failed.
There are two main reasons why a BIOS test fails:

• The battery on the motherboard has lost its ability to supply power. The system time and date are also affected by a bad battery.
• The BIOS was updated "incorrectly". This can happen if power is lost while updating the BIOS, or when the BIOS is updated with an update that was not downloaded from HP, or when a certain virus or malicious program modifies the BIOS data.

To resolve the error, do the following steps:

• Turn on the computer and immediately begin pressing the F10 key repeatedly until a Recovery Screen appears. If your computer originally came with Windows XP or earlier, press F1 instead of F10.
• A BIOS Setup Utility appears.
• Press F5 to restore the BIOS defaults.
• NOTE: If an error occurs or the computer locks up at this point, the default BIOS information has become corrupted. The computer requires service or a new motherboard.
• Press F10 to save the values and exit. Press Y to confirm before exiting.
• Restart the computer to see if the error continues.
• If the error no longer appears, you are done.
• If the error appears, continue using these steps.
  
• Replace the battery on the motherboard .
  
• After replacing the battery, restart the computer to see if the error continues.

1. If the error no longer appears, wait until Windows opens and set the date and time to current settings.
2. If the error still appears, the default BIOS information has become corrupted. The computer requires service or a new motherboard.

[Wingit]

Something has changed recently in the config? Indeed it could be complete config?
You have tried a clear-cmos?

[Mirinda]

Something has changed recently in the config? Indeed it could be complete config?
You have tried a clear-cmos?

in fact, everything is new, I installed the CPU in the motherboard coming out of the package, I plugged in and started