Having intermittent stuttering on a good rig

Hello all, first of all my specs are;
D900F desktop replacement:
Intel Core i7 960 3.2 GHz,
Nvidia Geforce 280m 1gb GDDR3,
4 gb DDR3 1333mhz ram x 1,
500gb seagate momentus xt hdd,
320gb toshiba 5200rpm hdd,
1920 x 1200 wuxga+
And im runnin on Windows 7 Ultimate 64 bit
I have all the latest drivers. All of them. Additionally i have kaspersky internet security 2012 installed as my antivirus software, and tune up utilities 2011 for maintenance. And i have steam as my gaming platform.

Ok, now, my problem is that im having performance issues i didnt have before. I have a stuttering issue which is making gaming annoooooyingly difficult. Not long ago, dunno, maybe like 2 months, i was able to play any game perfectly with 1920x1200 resolution and usually with the highest settings or ultra on not so demanding games but always with a constant 30+ fps at the worst, so it was really playable. Dont really know after what, my games started to lag. But mostly steam games. Like whenever i play Counter Strike : Source, eventho i have a really low as 15 latency, it feels like i have 600+ ping randomly at times. Or Team Fortress 2, i cant even play it on any resolution now. Changing the resolution or the lowering the graphics never solved it on any game. For instance, im also playing Dirt 2. Im driving for 2 seconds, and waiting for 1, driving 2, waiting 1. I cant figure out whats the cause behind it. As i said, just 2 months ago i was having at least 30+ fps on all games. My cpu and gpu loads and temps seems all normal. No overheating. And no background apps.

• So, first i thought maybe it was the dust on my fans. I've cleaned them. No difference.

• Then i thought it was a virus but nothing came up with the scan.

• I thought maybe it was caused by an update to my antivirus that made it scan my games while i was gaming and made exclusion rules for my games. No difference.

• Then i completely disabled my antivirus while i game. No difference.

• Maybe it was because my windows needed a formatting, i saved what i needed and formatted clean. Installed only the Os, all the drivers, antivirus, steam and 3 games(TF2, CSS, Dirt2). Now my games are more laggy.

• Thought it was the latest graphics driver. Reverted it to an older version from january. No difference.

• Searched the forums for the issues on the games. Did almost anything and everything. No difference.

Please help me. Please. Plea....

Try to 'repair' your windows via your install disk, maybe some of your system files are gone corrupted, because of the driver changes, or needless softwares, try to uninstall some softwares that you do not need, it used to help me w/ some minor issues.
I dont really understand this 'desktop replacement' phrase, do you have a laptop or dektop pc?
Your grapics card sound like a laptop card, but I don't know it, maybe it's too old, you cold buy a new card :$
If all else fails, maybe youre PCB (on the motherboard) is damaged somehow, that could cause that strange lag, try out stressing softwares, and monitor the performance on low and high tempretures.
good luck :)

Well its a laptop with an 17.1 inch display but its pretty big and heavy so you may not want to put this on your lap. :) And well, thanks for the reply but i currently dont have anything installed. its a fresh install. i formatted just recently and installed only the drivers and the games. And about PCB, well, i dont really know?

I see so it's a muscle laptop rig , the pcb is the printed circuit board, which is your motherboard basically. If this is a fresh config, it is not likely to be the problem but I'd give it 5%, though I have no more ideas.

well, i'm not sure about this but it seems i'm only experiencing problems with most of the games i launch via steam. I also play some pirated games like Duke Nukem Forever (on ultra settings) or Sniper : Ghost Warrior (max except shadows) with no problems at all. i am yet to confirm this with other games.. i think it would be acceptable if i encountered these problems with pirated games but with original and fully updated games to be so laggy for me is really unbelievable. I wonder if something is wrong with my steam app? Then again, after i encountered these issues, i did a fresh install. Even the steam and my games are newly downloaded. And im pretty sure its not a network thing, because i have this problems even with the offline games Whats up with that ?

Anyone?

Well, i formatted one more time to see if anything was wrong with my previous format. I reinstalled everything fresh and clean one more time. And i am one more time sad to say that nothing has changed. I didn't think i installed any tuning programs but I checked the msconfig nevertheless to see but couldn't find any nTune or anything related to it. My problem remains unsolved :/ And i have the same stuttering as you do except mine happens more frequent. How likely is it to be a hardware problem? Could it be something about my hdd or maybe my gpu? Maybe a damaged component? I'm out of ideas

Have you tried to remove the card and clean everything?

Well, since it is a laptop, it would most likely damage everything without proper tools. I've sent a mail about two hours ago to the company who've built me this lappy. But im not expecting them to reply me that quick. Maybe in 3 days i'll have a pro's opinion on the matter. The last option is to send it to them but i was hoping i could avoid any costs by searching on the net first. Guess i'm out of luck (and options). I hope it won't cost much if i send it.