C3/C6/C7 state slowing down Flight Simulator X

[Dave3000]

I have an i7 920 and when I turn on the C3/C6/C7 state support in the bios of my motherboard, FSX frame rate drops down to 23-24 fps from 25-26 fps when on the runway and not moving at LAX. Is this because of the latency from the cores waking up and FSX is not using all 4 cores every single second. This is the only game I have that slows down with this option turned on. Is there a way that I can use this option without slowing down FSX so that I can have 2.93 GHz for single core apps?

If I disable C3/C6/C7 then I can't get the 2.93 GHz core speed for single threaded apps and can only get up to 2.8 GHz and all cores are available at all times, so I need C3/C6/C7 turned for turbo boost to fully function.

Also when I enable C3/C6/C7 I get around 600 ms latency with DPC checker but if I disable C3/C6/C7 I get around 75 ms latency just idling at the desktop.

 

[PreferLinux]

Does it actually matter that the framerate has dropped when you aren't moving? Or does it drop at other times as well?

 

[Dave3000]

I don't move on the runway because I want consistancy in comparing fps. I just stay there for about 15 seconds to get an idea of where the frame rate spends most of it's time. Also regardless of moving or not, a faster system will show a higher fps.

 

[PreferLinux]

Sure, but what is the fps like when actually playing?

 

[BoomerD]

FSX frame rate drops down to 23-24 fps from 25-26 fps

Maybe your monitoring software can see that...you certainly can't tell the difference between those frame rates.

 

[JimmiG]

I think FSX uses extra cores only for processing new scenery as you fly, while everything else is handled by the first core. Are you sure you're testing 100% identical scenarios? Keep in mind that the frame rate can vary quite a bit in FS between runs, depending on the amount and position of clouds, the AI traffic schedules, where you've flown previously (some stuff is cached, some detail which is added as you fly near e.g. a city is not removed until you get very far from it).