Clocking the LC II / Performa 400 through 430

Since the Performa 400 through 430 and LC II all use the the LC II motherboard, historically, there is a limit as to what you can do to increase performance. Most speed increases to these machines come from Software. Low End Mac, The ULTIMATE Macintosh, and the Clockchipping Home Page are excellent sources of information with links for all kinds of speed enhancements. Study and use all the Software Speed Enhancement you can find.
I have two easy and inexpensive hardware alternatives that you might try as well.
I guess what got things started was the fact that my Performa 410 had lost its sound. While searching for information to repair the speechless motherboard, I came across Marc's page on Crystal Oscillator Speedup History I decided to give "my own variation" of the oscillator speed up a try, even though my Performa 410 was listed as not clockable. With a little experimentation I came to this result:

I disabled both oscillators by jumping the #1 and #2 terminals of each. Then I tied in a two prong 39.2MHz crystal a terminals #3 and #4 of the 25.1750 MHz Oscillator . * The oscillators are not mounted with the #1 pin in the same location so be careful which pins you are jumping. You will have to experiment to find out which frequency will work best for you. Output Enablers offers crystals and a two prong socket, to allow switching between crystals without soldering and de-soldering each time.
* Please remember that there is no guarantee that your board can be chipped.

The End Result
I wound up with stronger and faster graphics. Overall faster performance throughout. Print appears on the screen as you type it. Things start to happen while still clicking the mouse. And better yet, I can actually surf the net a little. Testing of the base 16 MHz system shows just a slight increase, but real life performance is dramatic. * I don't know if sound is affected, but I really don't think it would be. Even with the increased performance, the lack of sound made the next move inevitable.

Option 2
After I weighed all my options, I decided to install an LC III motherboard You can upgrade to an LC III (25 MHz) for almost nothing and then chip that to an LC III+ (33 MHz)! I found a board at Timco Computers, for $35. I also bought 16 megs of RAM since the 30 pin SIMMs in my LC II board won't fit the 72 pin slots on the LC III board.
The LC III motherboard fits in the 410 case exactly the same as the LC II. No modification at all!

So my Performa 410 has become a Perfoma 460 / LC III+. Faster processor, more RAM, and I was able to use the 512 VRAM card from the LC II to max out the VRAM.  Giving me thousands of colors and faster graphics. And last but not least, I Have Sound!
Thanks to Marc and the Clockchipping Home Page, Low End Mac, The ULTIMATE Macintosh, and Timco Computers in helping me make my Performa 410 a machine worth keeping for a while.

Good luck with either choice and don't forget about Software!