This is long but I really need help so please bare with me.
Months ago I overclocked my Amd Phenom 2 x4 955 Black Edition CPU from 3.2ghz to 3.8ghz. I also put the CPU voltage at 1.41. After the OC I ran Prime 95 for 4 hours and had no issues so I assumed it was stable with good temps. I've been playing games every day since then with no major issues...until the day I installed GTA 4. When playing GTA 4 the game will sometimes crash causing wierd artifacts and graphical glitches which force me to close the game. The crash also causes my open programs, Steam, and Google Chrome, to become unresponsive with graphical errors. The only way to fix this is a reboot.
I have gone through dozens of possible fixes and the only thing I've found that stops this from happening is going back to my CPUs default clocks. I played for weeks and put over 60 hours into the game without the OC with no problems. Decided to try the OC again, and 15 minutes into the game the crash happens. SO I know for a fact it has to do with the OC. But I believe there are two things that are causing my system to crash with the OC.
I believe it's either GTA4 or my PSU. GTA 4 is known for being an awful port and it's been reported that the game doesn't like overclocks. Some people have even had to disable the OC to even play the game. The other thing is my PSU. I'm not technically experienced with PCs especially not PSUs so I can't be as sure as other people. But I've read user reviews on Newegg claiming that the PSU doesn't handle overclocks well which causes a lot of issues. This is my PSU
The 955 should handle 3.8ghz or more if its a C3 chip, Have you looked at your temps while playing that game, To my surprise GTA4 will use the GPU to max 99%.
What I think might be happening is that the stock 3.2ghz might be bottle necking the video card, While you OC the CPU to 3.8ghz eliminates that bottle neck and allows your video card to work harder.
It might not be the CPU OC, But rather that video card. Have you OC the video card at all? Is it OC from factory? When you play GTA with stock settings, watch you video card usage and see where it sit at, OC the CPU and play GTA and see if the GPU usage goes up. Normally a bad CPU OC would cause a blue screen or Kernal Power errors in the error logs.
Stress the GPU if you can, Look up GPU Caps Viewer for a good video card stress testing program, just watch the temps!!!
I'm only noticing this with GTA4 and the GTA4 expansions. One time when my system crashed and all of my open programs became unresponsive, I tried to run Mount and Blade Warband but as it was starting there were artifacts and then it crashed. I'm almost positive the GTA4 crash did this though like it effects Chrome and Steam. And no I haven't tried it with a lower OC.
I have monitored temps when playing the game and even when a few of the crashes happened. The temps were as they usually are for both my GPU and CPU.
I have never OCd my GPU and it isn't factory OCd. I'll try to watch the GPU usage though and I'll try a GPU stress test.
The thing is, I've put 80 hours into Skyrim with my OC. Skyrim is a CPU heavy game and have never had this kind of crash. Have it nearly maxed out in 1080p with tons of mods too so I'd assume I would notice issues with that game too.
The GTA4 crash is very random. It could happen minutes after starting the game or after 8 hours of gameplay. And it's not like the game crashes when a lot is going on. I've played in full multiplayer servers with players, cops, and helicopters everywhere with no crash. Then it decides to crash when I go into an apartment to change my clothes.
GTA4 crash is normal sadly, But making things unresponsive and artifacting usually never happens under stable circumstances, I had GTA4 since it came out, and it heavly modded with the ice nhancer, color corrections, and Have used 3 different CPU's to play all 3 of them OC'd. I used a AMD Athlon x2 6000+ 3.2ghz OC, a Phenom II x4 940 3.81ghz OC, and now a Phenom II x6 1100T 4.1ghz OC and the game will crash no matter the system or hardware. Also used SLI Nvidia 9800GT's and now a single HD5850.
Also add a tad more Volts to the CPU, instead of 1.41v, Try 1.42 - 1.43v and see if that fixes the problem. And how did you OC the CPU? Did you use the multiplyer only or did you use the FSB/Bus Speed? Reason I ask if you OC with the FSB, it OC's not only the CPU, but RAM, CPU-NB, HT which could cause some instability problems. You can also bump the volts up on the Mobo NB, 90% of the time a voltage bump to the NB helps a CPU OC.
I would try to update to video card drivers properly if you haven't already, Or if you have updated it, downgrade the driver. Uninstall the Nvidia Drivers from your PC via control panel, Reboot when asked to, Install the newer/older driver and then reboot when asked. That should rule out the GPU even if it isn't the problem.
All that looks fine Temp wise, I was looking at screenshots of my Phenom II x4 940 at 3.8ghz ( http://i52.tinypic.com/2ed05s9.jpg Don't mind the red circle, That for an recall they had on my mobo) I needed around 1.456v to get it stable. Mine wasn't a C3 chip (don't think they made a PII x4 940 C3) so it needed a bit more volts, and 1.54v often 1.57v to get 4.0ghz stable on the DFI 790FX M2RS Mobo.
So adding more volts to the CPU certainly isn't going to hurt it at all and might cure your problem. Sounds like the 1.15v is the Mobo NB. The CPU-NB can take up to 1.55v like the CPU, but it wont need near that much, I would try 1.25v to make sure things are stable, then lower 1 voltage setting at a time until you crash or get errors. The Mobo NB I wouldn't go higher then 1.170v depending on the cooling really.
Like I said before, More volts isn't going to harm the CPU if you keep it below 1.55v, just don't go crazy and watch temps, To get yours stable I would personally try in between 1.41 - 1.45v to see if that helps. Phenom II's seem to hit a voltage wall, My 940 could do 3.6ghz at stock 1.32v, but 3.7ghz it needed at least 1.4v