Changed CPU Frequency, PC Not Starting

December 19, 2010 at 04:46:38
Specs: Linux i686, AMD64 2800
I have an AMD64 2800 chip and a GA-K8VT800 Pro motherboard. I stupidly changed the frequency from 200MHz to 250MHz. The PC beeps at me, long beeps of around a second every few seconds, no display, power LED light flashes rapidly. I tried taking the battery out over night but that did not reset the CMOS and the computer still beeps at me. The Clear PWD/CMOS jumper doesn't make any difference either. Have I blown something up by doing this? :(

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December 19, 2010 at 05:46:15
When overclocking cpu there are settings u need to change, one of them is reference clock(cpu speed=ref clock x cpu multi).
How to reset CMOS?
-unplug the power cord
-open side panel and locate CMOS battery(it look like small silver coin) on the motherboard
-remove the battery for a few seconds(15-30).
-install CMOS battery and close the side panel and connect the power cord.
-start the system and enter bios to correct some settings.

We can not fight new wars with old weapons, let he who desires piece prepare for war - PROPHET.

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December 19, 2010 at 07:37:11
Thanks for your reply, I was especially foolish to do this. I have taken the CMOS battery out, over night and that did not reset the settings. Is it possibly that I could have blown up the CPU / RAM or something else?

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December 19, 2010 at 08:45:36
Pay attention to what kuwese wrote - you MUST unplug the power cord! If you don't, the BIOS won't reset. And you do NOT need to leave the battery out overnight. As long as the power cord is unplugged, the BIOS will reset almost instantly. This following is from your motherboard manual:

If you want to erase CMOS...
1. Turn OFF the computer and unplug the power cord.
2. Remove the battery, wait for 30 second.
3. Re-install the battery.
4. Plug the power cord and turn ON the computer.

You obviously don't know how to overclock an AMD system. Changing the the CPU frequency affects numerous other settings - PCI, AGP, memory, HyperTransport bus, etc. All these settings need to be lowered before the CPU frequency is raised, otherwise they go WAY out of spec. Plus the CPU multiplier may need to be lowered as well. I highly doubt you damaged anything, you just over-overclocked & made the system unbootable.

Constant repeating beeping means the memory isn't seated properly in it's slot. Did you remove it for some reason?

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December 19, 2010 at 09:55:27
I did pay attention. I had removed the power cable. I hadn't touched the RAM. I tried to reset the CMOS many times with varying lengths of time with the battery (and power cable) removed, this didn't solve anything. The PC was working before I made the frequency change. I thought I'd trick the PC into thinking the hardware had changed by taking out the processor, RAM and graphics card and booted again. Switched off and then put everything back. My CMOS was reset and it all worked again.

I also learnt why I had had so many RAM issues with this motherboard. The board only accepts 4 blocks max in 3 slots. My RAM is double sided so I can only have 2 sticks in at once, 1 block on each side * 2! Also I read that the RAM should be in slots 1 and 3. I tried this and after the OS boots up, everything locked up and the numlock key light stays on. For some reason it works in slots 2 and 3.

I certainly didn't knock the RAM when removing the battery and the beeps and behaviour of the computer was unchanged from when i tried to reboot with the frequency change, so if it was due to unseated RAM then I am confused as to how that happened, or that my CMOS didn't reset...

Anyway it's all working now, thanks for your assistance. Although the hardware is a little old now, I hope what I have learnt here can help someone else in the future.

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December 19, 2010 at 10:29:39
"I also learnt why I had had so many RAM issues with this motherboard"

There's no reason why you can't run 3 double sided sticks of DDR400. The only thing that will happen is it will run as DDR333. If you're overclocking that is EXACTLY what you want anyway. As you increase the CPU frequency, the RAM frequency will also increase.

The problem with your board is that it doesn't have all the necessary BIOS settings to overclock properly. That's very common for VIA based boards. That's why nForce3 250 based boards were the board of choice for overclocking the S754 A64.

This is what you would need to do to overclock your system, IF you had the BIOS settings:

- lower RAM speed to DDR333 (166MHz frequency)
- lower the HT bus to 600MHz (3x)
- lock the AGP at 67MHz
- disable Spread Spectrum
- disable Cool 'n' Quiet
- lower CPU multi to 8x
- raise the CPU frequency to 250MHz.

The above settings will run the CPU at 2.0GHz, RAM at 200MHz (DDR400), HT bus at 750MHz.

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