From your replies and stuff, it seems as though you haven't read as much as i thought you had. I propose a max FSB test as a very good place to start... (anyone agree/disagree?)
Actually, no before that, lets go through the checklist right from the start, have you:
Downloaded CPU-Z
Downloaded Prime95/Orthos
Downloaded Speedfan
3Dmark06 trial version
(lets save memtest86 for later, if needed)
Those are 4 bits of ESSENTIAL software that every overclocker HAS to have. CPU-Z gives you a wealth of information and monitors voltages, multipliers, various clock speeds. This is a crucial piece of software as it lets you monitor what's going on everytime you boot up. Prime95/Orthos is a fantastic program. It puts your PC through a series of increasing stress tests. You should run Prime95/Orthos at level 8 for at least an hour between each relatively big jump (i.e. you'd run it for an hour at 2.8ghz, run it for 2 or 3 hours at 3.0ghz, run it for 6 hours AT LEAST on your final overclock) Speedfan lets you keep track of temperatures and manage fan speeds. The LOWER the temp of your CPU the HIGHER the STABLE CLOCK SPEED. I'll come back to temps a bit later.
Aftermarket cooler (99% essential ESPECIALLY on a Q6600 of all CPUs)
Adequete cooling (sufficient exhausts)
You should settle on a clock speed & cooling solution that means your CPU temperature rarely goes near 50, and certainly never exceeds 55 on a regular basis (degrees celcius) It is around 50 degrees in which the CPU becomes unstable as a result of heat.
System information. It is absolutely IMPERITIVE that you know all the neccessary information for your system. You should know (or at least have written down somewhere) your STOCK MEMORY TIMINGS (cas, ras, cas-ras, etc etc AKA 5,5,5,15 or whatever yours is) CPU MULTIPLIER, VCORE, VDROOP and MAX FSB (the important ones are in caps... errm lol...)
CPU multi is crucial to know, so that when you type in an FSB you know what clock speed it will result in
Vcore is important to keep track of (read up on net to see what sort of voltages other q6600owners are using)
Vdroop (how much your PSU/motherboard underestimates or under-supplies. Your fiddling around 0.05 volts at a time in most cases, so the slightest error in measuring can be an issue)
MAX FSB (requires more detail, so i'll go into it below)
List of things to do & order to do them in (IMHO from experience and other people's experience)
Run 3Dmark 06 to get a score, and to get an idea of idle/load CPU temperatures (move PC, use speedfan, get new cooler or whatever to get acceptable temps)
Run Prime95/orthos for 20 mins to get an idea of max temp you'll ever see (3dmark will give you a "everyday" idea of temp. Prime/Orthos will stress your CPU a lot more than normal everyday tasks)
Find max FSB:
loosen memory timings (hence you should know originals) by 1ns for each of the 4 main values
set RAM ratio to make the RAM speed below that of it's rated speed
put CPU multi on 3/4 or 1/2 of original
Keep on increasing FSB, then stress test, increase FSB, stress test...
You then know the max stable FSB, which gives you a fantastic bit of knowledge, you then know (for example) it is safe to use anything up to 423mhz. you can then work backwards (or forwards) with multipliers/FSB to find your max CPU speed. Then play around with voltage, FSB and CPU multi to achieve the highest clock speed with the highest FSB you can.
You can then set to work on memory, once you've passed a long stress test
Happy days
