New rig, help me fortify and maintain performance and stability.

I recently built a new pc, here are my specs:

Amd FX-8350

Asus Sabertooth 990 FX R2.0

OCZ Agility4 SSD - Windows 7 Professional

Hitachi 700GB HDD

2x Asus HD 7770 OC Edition

4x Corsair Vengeance 4GB

So I need help making sure that I have all of my system properties set correctly, current drivers installled properly, and have taken correct measures to get the most out of my system, and keep it well maintained.

I have already noticed a slight decline in performance I.E:  Loading programs, Windows experience index went from 7.3 to 7.2.  I would imagine that this was from installing firewall/antivirus/other programs that run constantly.

Any help would be greatly appreciated!

(Can't find spellcheck, sorry for any misspelled words!)

Make sure all your drivers are up to date visit each manufacturers website and download the proper drivers for your hardware. Then make sure Windows is fully patched. Also check in device manager to see if there are any unknown devices are devices that have red "x's" on them, there should be none.

Make sure your motherboard has the most recent BIOS installed.  That is a fairly new CPU and an updated BIOS may iron out some issues.  I have version 1 of your motherboard with an FX-8150 and had to update the BIOS to get a game to run properly.  If you think your antivirus software is slowing things down, you can try Microsoft Security Essentials.

Would you recommend Microsoft Security Essentials?  I used AVG for the longest time, but on this build I chose Avast!.... Kind of sucks.

MSE is ok AVG used to be better but its slipped over the past few months.

MSE is adequate and is light weight so it generally won't slow down your system or use a lot of memory. 

So After installing my FX-8350, CPU-Z  shows the core speed switching from 1404.8 Mhz with a multiplier of x 7.0, to 4113.9 Mhz with a multiplier of x 20.5.  Is this an energy saving setting from the bios?  Or should I be worried >.<

Yes, that's the Power Management working.  It must be set to Balanced.  If you want  to change that, go to Control Panel -> Hardware and Sound -> Power Options.  

There are usually three options:  Balanced, Power Saver, and High Performance.

With High Performance, the core speed will always be at the maximum, but will use up more electricity.

The power stepping and shutting down of cores is controlled in the BIOS, this is normal.  Generally, the faster your CPU goes, the more power it draws. 

Sweet, thank you guys.  So what are some general things y'all do to a new build and fresh OS install to get performance at its highest?  Settings, etc.

There's not really much you need to do to a new OS install, just make sure your graphics drivers are up-to-date and you use a lightweight security product.  If you're using Windows 8, you don't really need to do the last one as it has Microsoft Security Essentials integrated with the OS.

This is completely optional but you could overclock to push out more performance.

Yeah I may.  What's the best way to test stability after an overclock?  And what would be a good tempurature to stay below?

For a CPU overclock, first use Intel Burn Test and set it to maximum and if it passes then run Prime95 overnight. Try staying below 62C for the 8350. I wouldn't bother overclocking your pair of 7770 because it has already been factory overclock and it should be fine.

Here's a great guide on overclocking the Bulldozer cpu that was done by OverClocker - http://www.overclock.net/t/1140459/bulldozer-overclocking-guide-performance-scaling-charts-max-ocs-ln2-results-coming