I upraded to intel 3770k 3.5ghz with Asus sabertooth z77. I use to have a intel core 2 duo e8500 3.14ghz and Asus lga775 motherboard. I still have the same video card a Gtx 570 hd 2.5 gb. I just connected my hardrive to the new motherboard and installed all the new drivers it needed. I started up Fallout new vegas and now when I go near any NPC out doors the frame rate drops to 5 fps and stays there no matter what I do. I started over again and this time I unticked every mod I had and when i get up and walk to the skill machine, the frames drop the exactly 30fps and stays there. I loaded up the old save and this time I went to an in door location with npcs and the frame rate stayed at 60fps. Heres the kicker. I have fallout 3 goty also and it runs the same after the hardware upgrade and a little better since the processor is better. I have a good amount of mods with both games, NMCS textures with both games also. I did every little INI trick on the internet also. I contacted bethesda and all they did was tell me to uninstall everything on my harddrive related to nexus mod manager and fallout mod mananger and reinstall new vegas. I am not going to uninstall all my mods due to the fact that i have tinkered with the mods to make them run without crashing. They just wont answer my question as to why Fallout 3 runs the same and New vegas runs like crap.

They won't be able to either. No one will. You won't get single specific answers as to why if that's what your looking for. It doesn't work that way.

First I would verify FNV game cache. It never hurts to try that.

Next you should try to get it as close to vanilla as you can. You mentioned unticking all your mods already. You should also disable archive invalidated, enb series, sweetfx, etc,

as well as refreshing the .ini files. Backup all .ini files first. If you made alot of changes to them then the changes will be lost. If you changed the default .ini then you need to back that 1

up as well and do a game cache verify (it will download the original again) since the game creates the other 2 .ini's based on the default .ini. Ill assume you know what .inis im talking about

since you say you use alot of mods.

You might also try refreshing your video card driver.

As to connecting a new MB to an existing Windows install, that can have mixed results. It is recommended that you repair/reinstall the OS if you do this. You really need to get rid

of all software from the previous board (drivers, applications, etc). Making peripheral upgrades or even CPU upgrades are fine as you generally don't have to reinstall the OS. The MB is the foundation of everything really

software and hardware. The process is simply too complicated to verify if everything installed properly and the new MB has everything it needs in the right places. Consider this as a possibility anyway.

YOu can try to post a dxdiag. It wouldn't hurt to see if that points to any possible causes. http://www.gamesas.com/topic/1122570-how-to-dxdiag/