Overclocking problems... PSU limitations?

Hey everyone

It's my first time posting in any forum along with trying to overclock my first custom PC. I have an e6750 2.66ghz C2D that can't go pass 2.80ghz. I see everyone getting that CPU over 3.0ghz which makes it odd for me. So far I think the answer is that my PSU is insufficient. Anyway these are my computer specs.

ocz powerstream 520watt
evga 7150/630i
evga 8800gt 512mb
intel e6750 2.66ghz w/ arctic freezer 7 pro
2x corsair xms2 1gb ddr2 800
western digital raptor x
4x seagate barracuda
nec nd-3550a dvd-rw drive
lite-on blu-ray drive
3x 120mm case fans
2x 80mm case fans

Further detail is that my CPU runs idle between 35-39 degrees C which I think isn't that high and maybe 5 degrees higher on load. According to eXtreme Power Supply Calculator (google the name to find), I'm running at about 516 watts which is almost at the peak of what my PSU is. It may not be that accurate but it does give me hints that my answer would be to get a better PSU if I want to overclock. If I do need a new power supply, how many watts do you guys think is recommended to be safe? 600w? 700w? 800w? Any answers to what my problem might be which is preventing me from overclocking my CPU higher is appreciated.

when its the PSU you will know it, most PSUs will refuse to start again after an overload, and the whole system shuts off, if its some other part generally you just fail POST or crash somewhere in the boot and reboot or something

My guess is your hitting the limit of the CPU at that voltage or the RAM is giving out on you, so first try changing the RAM to FSB ratio and/or loosening the timing, the next option would be to try boosting the voltage of the CPU a bit (that is required for any large overclock).

Then looking at the motherboard it does not seem to be that great at overclocking itself, when you overclock the FSB to boost the CPU it will also overclock at least the north bridge, and if you go for a big overclock your motherboard better have some big heatsinks, and i see mixed reviews on newegg about that. From the pics the heatsink looks pretty small and aluminum, compare that to some of the more expensive boards with a large copper heatsink.

Thanks for the reply edman

I think you may be right about the motherboard because I have seen mixed reviews on overclocking it. Some say it does well and some say it doesn't. I know it shouldn't be able to overclock well seeing that it is a micro-atx. I just thought I would get a little farther than where I'm at now. Would setting my RAM timings back to default help though? I actually changed it to 4-4-4-12 before I even started trying to overclock my CPU. I have also messed with the fsb ratio linked and unlinked with same results. I did remember increasing the CPU voltage to 1.325 and it actually didn't make any difference. Any higher would cause my PC to just constantly reboot every 10 seconds. Now that's what seems to be a PSU problem overall from your info. I've been stuck at 2.8ghz from all the results. Anything higher would cause my motherboard to refuse the new settings and change it back to default or tell me to do it myself. My guess is that your right about the motherboard. Any recommendations on decent overclocking board that's non-sli/crossfire.