PC Lag/Stuttering

[Nebulously]

Hopefully this is the right place to post this. I'm thinking it's a hardware issue, but not 100% sure. Anyways, I don't know what the problem is. I built this computer about 4 years ago but have upgraded various components every couple years.

Symptoms: Started occurring about a month and a half ago; before which it was running fabulously. When multi-tasking, mouse movement will slow/stutter, internet tabs will not load, video playback lags and has stuttering noises. It also happens sometimes when not multi-tasking, but becomes more apparent with more tasks running. Will occasionally get random crashes. Transferring files to flash drives takes WAY too long. CPU/RAM does not even come close to maxing out during these occurrences according to the Windows 7 monitoring gadget. Also, the problem tends to become worse if I plug in my two external hard drives that I use for storage.

At first I thought the issue was my hard drive/windows or a virus, so I recently replaced the drive with a SSD and reinstalled Windows. I also ran full system scan of all hard drives with Avast and Microsoft Security Essentials before and after replacing my boot drive and reinstalling windows; no viruses were found. Soon after the reinstall, I was experiencing the same problems even with only the new SSD plugged in. I thought it could be a processor/RAM issue then, so I used both Memtest86+ and prime95 to stress test those components. Both passed without any errors after leaving each test running for 8+ hrs. I figured I should test my graphics card while I was at it, so I removed it and have been running on the integrated Intel graphics and still have the same problems. Only thing left could be MoBo or PSU or something I haven't thought of? I would appreciate some input, as I have no idea what the problem is. Thanks.

Computer Specs:
Windows 7 Ultimate 64bit
ASUS P8z68-v Pro MoBo (newest BIOS installed)
Corsair HX Series 620W PSU
i7-2600k CPU @ 3.40 GHz
12 GB (3x 4GB DIMM) G.Skill Ripjaws DDR3 1600
Boot Drive: Intel 330 240GB SSD
Internal Storage Drives: WD Black 7200rpm 1TB & WD Black 7200rpm 750GB
PNY GeForce GTX 470 GPU

 

[Jetster]

Update all the latest drivers from the Motherboard Manufactures web site including BIOS.

Check the SATA cables

Only run two sticks ram sense your board only supports dual channel. 8 Gb is plenty at least until you figure this problem out

Also pull the GPU and run integrated and see how it runs

 

[Nebulously]

Update all the latest drivers from the Motherboard Manufactures web site including BIOS.

Check the SATA cables

Only run two sticks ram sense your board only supports dual channel. 8 Gb is plenty at least until you figure this problem out

Since I reinstalled windows, I also installed all the updated drivers from Asus for my MoBo.

How would you suggest checking the cables? Making sure they are seated properly or switching them out with new ones?

I'll go ahead and remove the extra DIMM as well

 

[DRDNA]

it sounds like heat throttling
..Did you monitor temps when stressing the cpu?
Did you check your heat sync for dust build up?
Maybe some new paste?

 

[Nebulously]

it sounds like heat throttling
..Did you monitor temps when stressing the cpu?
Did you check your heat sync for dust build up?
Maybe some new paste?

No, I didn't monitor heat while stress testing the cpu. I can try replacing the paste; haven't done that for about a year. When I installed the SSD, I thoroughly cleaned the fans/heat sync though.

 

[DRDNA]

No, I didn't monitor heat while stress testing the cpu. I can try replacing the paste; haven't done that for about a year. When I installed the SSD, I thoroughly cleaned the fans/heat sync though.

monitor your temps while stress testing the cpu first. use RealTemp
http://www.techpowerup.com/downloads/2089/Real_Temp_3.70.html

 

[Nebulously]

monitor your temps while stress testing the cpu first. use RealTemp
http://www.techpowerup.com/downloads/2089/Real_Temp_3.70.html

Ok, so I ran the stress test again with temp monitoring for a little over 6 hours. Highest temps I saw were 64 C. So it's not a heat issue...

 

[Hellraiser1981]

Go into the BIOS and disable all onboard devices (parallel, network, sound,etc) and try it.
Did you clear the CMOS yet?

 

[Binge]

Take apart the whole thing, re-seat all devices after you first test with bare mobo/cpu/one stick of ram and running off of your on-cpu video. If your regular office-style applications still stutter you've just narrowed down the problem areas of your computer. Try every stick of ram in each slot if you want to be super thorough.

 

[Nebulously]

Go into the BIOS and disable all onboard devices (parallel, network, sound,etc) and try it.
Did you clear the CMOS yet?

Haven't cleared CMOS. I'll try that and reseating everything. From there I'll move on to disabling onboard and/or bare setup like poster below you suggested.

 

[itsakjt]

Try a live copy of linux. Or tell us that when you attempt to install Windows, does it stutter in the installation section? This will make it clear whether its the software or the hardware. If it is the hardware, then your motherboard might be at fault. I had a similar problem when one of the 3 phase CPU VRM burnt on my Pentium 4 Intel Motherboard.

 

[lyndonguitar]

Its definitely on the Mobo, its connections, ports, etc

You've checked everything except the mobo and the PSU, and PSUs either work or don't work and they don't hinder performance. so mobo