[ubuntu] Computer ruing slower after hardware upgrade

So, I have an older desktop that I decided to "upgrade".
By upgrade, I mean max out the motherboard and see if I could get a few more years out of it.

Here is what I started out with.

MOBO:
MSI K9A2 Platinum

Processor:
AMD Phenom X4 9950 2.6 GHz Quad-Core

Memory:
G.Skill 4GB 240-Pin DDR2-1066

Video:
ATI Radeon X800 Pro 256MB

Power Supply:
GreenME 650W

Here is what I ended up with/currently have.

Same MOBO.

Processor:
AMD Phenom II X4 965 3.4 GHz quad core socket AM3 CPU Deneb

Memory:
G.Skill 8GB 240-Pin DDR2-1066

Video:
PNY NVIDIA GeForce GTS 250 1GB Video Card PCI-E 2xDVI VCGGTS2501XPB Blue Board

Same Power Supply.

I am currently ruing Ubuntu 15.10 and am using the proprietary drivers.
The system seems to think the processor is an 800mhz processor!
What the crap!
Tasks that I was able to do previously, are now lagging and ruing very slow.
All of these components are supported by the motherboard as per the website.

Any help would be appreciated. I'm not expecting blazing fast, but my youtube videos shouldn't be buffering on HD when before, they were streaming.
Also, video rendering is slower, when it should be much better with this card. Again, not super fast, but 256MB to 1GB should be substantial I would hope...

Thank you for any help!

Also, please, have a wonderful day.