Sound crackles and FPS drops with new gpu

I installed a new Nvidia Geforce GT710 and so far it's working pretty good

except for

a few games, namely FSX, have massive FPS drops and related sound 'crackling'. This also happens when I webpages that contain a lot of things such as the Toms Hardware GPU forum.

I have the latest audio drivers and I cannot seem to identify a sound card. If there is one, it's pretty small or hidden. There is a speaker at the front but unplugging it from the mobo does nothing. I also tried the jacks at the back, no joy.

I've tried resetting the BIOS, but that did not work either.

My dell's tag is 96XTT1S. Just replace the ATI card to the Nvidia Geforce GT710.

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I ran latencymon, this is what it came up with:

"Your system appears to be having trouble handling real-time audio and other tasks. You are likely to experience buffer underruns appearing as drop outs, clicks or pops. One or more DPC routines that belong to a driver running in your system appear to be executing for too long. Also one or more ISR routines that belong to a driver running in your system appear to be executing for too long. One problem may be related to power management, disable CPU throttling settings in Control Panel and BIOS setup. Check for BIOS updates."

Cannot find anything about CPU Throttling in the BIOS or Control Panel. CPU is an Intel Core Duo 2.

Mellon Head said:

Try disabling Speedstep in BIOS, if it is listed. It may not be, being that your computer is a Dell.

Speedstep was disabled when I got there.

One thing I forgot to mention was that it (driver) use to crash frequently and recover. I found the disk that came with the GPU and installed that and the crashing has nearly stopped, there is just one at random points, sometimes not at all. Still doesn't work for the main issue though.