Get another processor. I've got two Celeron 500's on my dual mobo. They post at 625 MHz but are unstable at default voltage and my mobo also lacks voltage modifiers in BIOS or with jumpers on the board.
The gain from going from 75 MHz bus to 83
MHz is nothing.. I'm getting myself an AMD rig very soon. I've ignored the truth for too long.. Imagine, I must've overclocked 12-14 AMD Athlon cpus (Slot-A and socket) belonging to friends of mine and tried to convince myself that the performance I had was good.
A classic Athlon 500 with a GeForce 256 DDR get 4040 3D Marks 2000, my rig with a GeForce 2 GTS get 3350 because of crap cpus. And then I've not mentioned 3D Mark 2001 or any other benchmarks for that matter.
A Duron 1 GHz with my card gets 2500-2600 3D Marks 2001 and I get 1150 marks. That's absurd. At least they only cost twice that of the Duron when I bought them.
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Pump:Eheim 1048,
Radiator:LPD radiator 100x150x20mm,
CPU block:DD Maze-2,
GPU block: DD GPU block,
Chipset block:Zalman NB32
AMD XP 1500+, EpoX 8K7A, PoV GF3Ti200
Pic of my YY-cube