Hi,
From what you say in your first post, that 'strange melody' as you put it sounds like a failure in a POST test.
A Power On Self Test is carried out when you swicth on the PC. It tests the motherboard, video cards etc. If something fails then the computer beeps at you. What those beeps mean depends on your mother board. See the link below for examples
Because your old processor worked at 266 MHz, when you installed the new processor, chances are you needed to change the clock speed for your new 450 MHz processor.
I beleive your motherboard should automatically change the settings (something it calls SeePU !) when it detects a new processor
I think the 266 processor used a 66MHz front end bus (x4 for CPU speed), where as the 450MHz had a 100MHz bus (x4.5 for CPU speed).
Now if the above is true then one thing you'll need to check is the speed of your RAM.
Also (although I'm not sure on this one), the voltages required for the CPU may be different, you'd have to check.
Any Help, Yes/No let me know
Regards
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Is not a fool a wise man in his own eyes - Proverbs