Hey guys, this is the first time I'm bothering to try overclocking since Crysis demo didn't run as well as I would've liked. I tried 3.2ghz (8x400) with a 1.325 vcore, and it posted just fine, Vista booted fine, and I let it run in Prime95 v25.4 for about 8 hours, and it was stable. Idle temp is around 32-34C, and haven't tested load, but it was about 50-52C when I checked after I closed Prime95. I thought it was then time to test games. For this I tried The Witcher. Fairly recent game, not too stressful, not too easy either. Ran fine at first but then gradually it'd start to hiccup and stutter, and then hang. Does anyone know why this is? Shouldn't it be considered stable if I ran Prime95 for that long and Windows and temps were ok? I've also tried various other settings and the one other stable one I got after 8+ hours of Prime95, The Witcher was choppy. I'm kind of confused on the problem here. To me it seems like it might be a lack of power, but then it ran stable for so long, so I'm not sure?

Anyways here's my specs, if anyone could help I'd appreciate it:

C2D E6600 (Thermalright Ultra-120 Extreme w/ Scythe 120mm 1600rpm fan)
Gigabyte 965P-DS3
2X1GB OCZ Platinum RAM (PC6400, 800MHZ, 4-4-5-12)
Silverstone Zeus 650W PSU
eVGA GeForce 8800GTS 640MB (Thermalright HR-03 Plus)

Oh and I also changed the RAM voltage to +.3 since it's rated as 2.1v on OCZ's website.

First off do you see any of these problems when you are running games clocked at the default settings? The Crysis demo not running well has been reported by a lot of people. It's probably a driver problem (Nvidia). The Witcher is also fairly new. Your going to see bugs until it's patched. Your E6600 is more than adequate to run those games. To be honest you would get better performance gains by overclocking your video card. The E6600 is not the weak link in this case. Also if you're running with the FSB\CPU unlinked you don't need to increase your RAM voltage. 2.4v is quite high for PC-6400 @ 800Mhz. I think the normal voltage setting for standard PC-6400 is 1.8v. Performance RAM increases a bit though. However I would stick with 2.1v - 2.2v if you're not overclocking you RAM that is

Yeah it runs just fine actually without overclocking. About what you said on my video card, that's what I was thinking, but based on benchmarks I've seen, it seems more people get performance gains from overclocking the CPU than the video card. Besides, my CPU was like half the price of my video card.. I'm less willing to experiment with that. As for the RAM, I think maybe you might've misread something? I have it on 2.1v. Anyways, do you have any idea though why it'd be stable in Prime95 for 8+ solid hours but crap out on me in gaming in any setting? =\ Kinda weird..

Prime95 test CPU and Memory, but not the HDD. HDD is the biggest bottlenecks in PC, stuttering can happen from this bottleneck. So, maybe the CPU and RAM are running very fine, but your HDD are fill with fragmented files so don't get surprise if your games are stuttering. Defrag your HDD.

I defragged last week though. If it was my hard drive, wouldn't the problem show up when I run at stock speeds too?

I may have read it wrong but I thought you said your RAM's voltage is set at 2.1v with a +.3 overvoltage = 2.4.

slicessoul has a good idea but I don't think this is the case here. You'd here your HD chugging away and would still have slight stuttering even at default clocks.
It really depends on what you are using your PC for. If you want games to run smoother then a medium overclock on the CPU and a healthy overclock on the GPU is probably what you're looking for. If you're going for a better SuperPI score than CPU overclocking will definitly help. Of course heat is always the enemy so you want to get a good mix of the two with minimal temps when gaming.
Check out RivaTuner for video card overclocking. It's very easy to use and the chances are very low that you'd fry your card. The worst thing you can expect is a system crash or lock up (as long as you do it smartly with small increments). I bet you could safely get another 30-50Mhz on the clock and another 75-150 on the memory. There's no messing around with voltages since Nvidia has them locked through Hardware. Bastards! I have one BFG 8800 GTX OC and had no problem going from 600Mhz to 630Mhz on the core clock and 900Mhz to 1050Mhz on the memory using BFG's factory air cooler. With water I gained more but will still hit a wall around 680Mhz\1100 beacuse of the locked voltages. Just make sure you unlink the core and shader clocks in RiveTuner as the shader clocks are already very fast and are quite touchy when it comes to speed increases. If you need a hand or have another question feel free to ask.

I'm a bit confused. I thought default BIOS voltage was 1.8, so to get 2.1 like it says for my OCZ RAM, I thought I was supposed to set it to +.3 overvoltage? Also, I might consider overclocking the GPU, but if the CPU's not even stable then no point. =\ Do you have any idea why I'd get the problems I'm getting? As in the settings that are stable in Prime95 for a while will start to lag and stutter after I'd say 30-40 min of gaming in The Witcher? Is this a sign of not enough power? I really would rather not go too far past the recommended voltage settings, and I hear of some people getting 3.2GHz and only needing to increase voltage slightly using only stock cooling. I know every system is different but it's a little weird that I can't get the same results as some of these people with the same CPU and motherboard.

965P-DS3 set RAM voltage at 1.8v (BIOS default). So if the OP set the BIOS RAM voltage +0.3v means he'll get 2.1v. This mainboard doesn't automatically set the RAM voltage as the RAM needed.

For the OP,

When CPU doesn't have enough power, BSOD will occur. When GPU doesn't have enough power, signal lost and BSOD will occur.

Try to test your RAM only with Memtest.
btw, is it OCZ rev. 2 ? on 800MHz, set it at 4-4-4-15 2.0v.

Check your BIOS for AHCI and Native option, i know Vista can support them, but after i tried by myself, disabling those options make OS run faster (Vista and XP).

When you overclock, disable the EIST, virtualization, legacy USB and save your overclock setting in BIOS profile. Set your PCI-E freq at 100, set FSB and g(MCH) +0.1v for stability.

Did you change anything on swap files ?

Are there any background applications running or unused services or task scheduler ?

I never received a BSOD. Just mass stuttering from both my audio and my video in The Witcher. At one point it froze and I needed to reboot (or it could be it was an insanely long lag and I just didn't have the patience to wait it out). And nope it's not revision 2, it's the original, with 4-4-5-4-15 timing at 2.1v. Should I still do 2.0v? I never had AHCI enabled to begin with, and I disabled EIST, & virtualization, but I'll have to check on the legacy USB (though would that particular option make any difference?). PCI-E frequence was also at 100, though I'll try the FSB and g(MCH) to 0.1v like you suggested. And nope, never touched swap files and nothing unused background stuff.

Anyways, I'll try the things you suggested that I didn't do last time and tell you how it goes! Thanks!

Probably it's the games who need a patch, check it's website or some forums for this games. Try with another games, maybe Crysis demo, run it on high settings and 1024x768 or 1280x1024 resolution or maybe if you have other games and see how's your rig performs.

Set your RAM as the RAM specs.

It's mentioned in Gigabyte site that legacy USB can create problems while overclocking. In my experience, disabling legacy USB helping mainboard to load the overclocking profile.