My Overclocked NES!

[133MHz]

Hi everyone!

What you are about to see here may look like your typical run-of-the-mil American toaster NES:


But a closer inspection to the underside...


Yup, it's overclocked!

Overclocking your NES is easy: You just have to cut the CPU clock pin and feed it the clock of your choice, but 12X the clock speed you want. For example, the NES generates a 21.47727MHz clock signal for its CPU and PPU, which gets divided by 12 by them internally yielding a 1.79MHz effective clock speed. So to make it run at 2.0MHz you have to feed it a 24MHz clock signal.

What is the benefit of overclocking it? Does it make your games run faster? No, like overclocking your computer, it boosts the CPU's processing power, getting rid of the annoying slowdowns you get in so many games for example, when you get too many enemies onscreen at a time. Now you are playing with POWER! 

Not all NESs overclock the same, some can take higher speeds than others. Too high of a clock speed and you get massive glitching all over the screen and crashes (Note: You can't overclock the PPU, doing it will raise the video output above 60Hz, rendering it useless for TV display). You have to try different clock speeds until you get the best for your NES. I tried about 6 speeds, from 1,3MHz (that's actually underclocking it ) to 3,75MHz! and found 28.3220MHz (or 2.36MHz) to be the most stable and glitch-free. A good source of TTL crystal clock generators are old computer motherboards and add-on cards. I got mine from an old ISA video card 

A little downside of the overclocking is that since the sound generator is inside the CPU, raising the clock speed will raise the sound pitch as well (I actually find that pretty funny, the dog barking in Duck Hunt sounds like some tiny poodle ).

I installed a switch below the unit to switch from the stock speed to the overclocked speed (below the unit to avoid ruining the aesthetics of the system). Here's how it's all connected:


The clock generator takes 5V from the output pin of the voltage regulator, and a ground (I used the RF shield as a ground point). The switch lets me select between the original clock (taken from the PPU clock pin) and the new clock. Use the thinnest and shortest cables you can to maintain the signal quality.

Here the wiring is nicely routed and the clock generator glued to the case with a little hot glue.


When I get my TV capture card working properly I will upload some comparison videos to my Youtube account so you can see the difference between speeds.

Comments? Questions? Suggestions? I'll be glad to hear them!

[satoshi_matrix]

Now that's awesome.

What games does it noticeablly speed up?

[FamicomFreak]

good stuff

[JC]

Awesome information. I hadn't heard about this before. It'd be neat to see something like that for the Famicom.

[133MHz]

Judging by the mainboard pictures I've seen of the Famicom, it is technically possible (it uses the same Ricoh 2A03 CPU with the same pinout). I know you guys can recall many times you get massive slowdowns in NES games . The only thing that crosses my head right now is sometimes in Megaman 3 with some enemies that spawn another enemies and in Super Mario Bros 3 when there are lots of goombas. I'm testing my game collection and picking some examples .

P.S:Famiclones with NES-on-a-chip gloptops are not overclockable, since the CPU and PPU share the same gloptop there's no way to selectively overclock the CPU while keeping the PPU on stock speed. Replacing the crystal oscillator on these will overclock both units and render the video output useless.

[JC]

I always have problems with shooters, especially Life Force. I bet Recca would be similar because of all the shit on the screen at one time. I might have to try this sometime soon. I'm not very good with modifications, but we'll see...

[Jedi Master Baiter]

Try the 4th stage of Gradius II.

[133MHz]

Spent all afternoon trying to make my TV capture card work (it suddenly began recording full of video glitches - tried reinstalling its drivers, updating them, moving it to another PCI slot, reinstalling video card drivers, replacing the monitor (!) to no avail). Luckily it now looks less shitty than before (kinda decent), so I recorded a short video testing SMB3 overclocked! The slowdown is not as massive as in another games, but it's the easiest to film. Try it!

Video http://www.youtube.com/watch?v=g4m-wyFC5-M

I'll be uploading more soon!

[keiffer01]

That's cool man! Will you write a step by step guide on how to do this?

[133MHz]

Yup, I'm waiting for my sister to return my digital camera

[satoshi_matrix]

I'm not exactly what you'd call techinically minded...would you consider modding my own NES if I mailed it to you? How much would you want for that?

[133MHz]

Wouldn't shipping a thing the size and weight (think the RF shielding!) of an NES from Ontario, Canada to Santiago, Chile cost a small fortune? You'd have to pay shipping both ways and I have to see if I have an appropriate clock generator (or you can send one of the desired frequency). As for how much I want... I think an interesting NES/Famicom cart inside the NES would be great

[Jedi Master Baiter]

Try the fourth stage of Gradius II.

[133MHz]

I don't have Gradius II, sorry

[Profeta Yoshitake]

I always have problems with shooters, especially Life Force. I bet Recca would be similar because of all the shit on the screen at one time. I might have to try this sometime soon. I'm not very good with modifications, but we'll see...

Recca is a true humiliation!
There are plenty of sprites and almost no slo-mo!

What about Parodius?!

133MHz!!!
Does the overclock alter the sounds too much?