Inexplicable stuttering and lag in games - diagnosis please?

[Inquisitor Z]

Hi, please excuse the wall of text. I really, REALLY need advice on this issue.

So, for some time now, since I built my new gaming PC, any games that I've attempted to run will suffer from a number of common issues.:

1) ------------------------
Upon starting the program, they will run smoothly - however, as a single session becomes longer, the game will take longer to load content , and certain heavy-action or graphics intensive scenes in some programs have the potential to cause the entire game to crash-to-desktop without warning.

2) ----------------------
No matter which game it is, from the least taxing to the most resource-heavy, there is what I refer to as a "stutter". I'm not sure of the actual term, but this is the jist: every couple of seconds, the game appears to "skip" a frame, as if it is lagging, and occasionally when it is worst little distorted bars or blocks will appear, before the game unfreezes and continues to stutter as usual.

I've seen the words "artefacts" and such thrown around here and there, and I'm not sure if that's the proper term. Regardless, it can be incredibly annoying in a game where play is normally smooth and pretty. I've tried playing on the lowest graphics settings possible - it makes only the slightest difference. The stutter is always there, and even YouTube videos suffer from it sometimes.

3) ------------------
Finally, and this is the strangest part, any upgrades I have made thus far have not helped the matter at all.

I have 3 case fans and 2 inside my graphics card, and I am thus skeptical to believe the problem could be overheating (though I might be wrong??)

My graphics card is an ASUS DC2 Geforce GTX 670, supposedly a fairly high-end card (it certainly cost me enough). But still, no effect - the stutter does not seem to be a graphics-related problem. I have updated drivers to latest, etc. , but the fact that this same stutter appeared when I had my old card suggests that the GPU is not the issue.

I installed 16GB of G.Skills Ripjaws memory to replace my old generic 8GB. No effect.

I have four AMD Phenom II X4 965 CPUs installed. My motherboard is the Gigabyte GA - 880GM - UD2H model. I don't know if they could be the source of the problem - perhaps they are not suitable for my needs? They were reccommended to me by a friend, so I may have bought them unaware of issues.

Finally, there is my PSU. I'm not sure what PSU I have installed, or whether the above could be symptoms of inadequate power. I've seen some similar symptoms in relevant threads, and I do occasionally suffer from random crashes and shutdowns. But I think I would be having more extensive errors if it were a power issue?

The un-removable stuttering, lag and loading slowdown even in the lowest-graphics offline games has become maddening. ANY ADVICE would be hugely appreciated - it is driving me insane to have spent all this money for a mediocre experience.

ADDITIONAL INFO: Any applications I am running are also liable to freeze up, stop working or crash at any time. No just games. While relatively rare, they are nearly as annoying.

 

[HEXiT]

some good info but your missin some. what hdd do you use. what psu brand and power.
what temps are you getting and did you fresh install when you upgraded your gfx.
smooth then skip, smooth then skip normally points to an fps issue cause by a bottleneck. this will show up more with games that use 1 or 2 threads. so the original crysis would be a good test to run. as would starcraft 2.
is your fps consistent at both low and high settings?.
measure them with fraps or use the games own fps display if it has 1. play the first 30 seconds to a minute of a level. quit. drop the settings save em then reboot the game (reboot the game because changes in settings are not often aplied till the game restarts.)
artifacts... range from little discoloureds squares to invisible polys... big black polys that stretch off into the vanishing points in the distance is usually a sign of weak physx support. artifacts appear for a few of reasons. not enough power, to much heat, damaged gpu. can you hear any high pitch whistles comming from under the fans about mid way down the gfx card? if so you may have an issue with the voltage controls.

as for the random freeze up it could be you havent set the high precision evenet timer in bios.(often called hpet, pet, high precision mode and so on, its often found in the same place as the options for ahci) make sure its enabled and set to 64 if your using vista 64bit or later.