Started this thread in mid-2014, re-emerged, corrected, and updated in July 2016. A number of games suffer from low framerate on the N64, so I tried a few swaps on the crystals, RDRAM and carried out a CPU multiplier mod to try and see how they impacted overall performance on general gameplay. How clock is generated and distributed on the N64 board (verified with oscilloscope and crystal swaps), this is an NTSC version, thus X1 is 14.318 MHz: Overclocking: X1 (Video Clock VCLK) -X1 sets the video and audio bandwidth for the RCP (VI and AI), DACs, and encoder. -VCLK is a 40%/60% duty cycle signal from clock generators. -Putting a higher clocked crystal will increase sound pitch, and distort video color – likely from feeding the analog encoder a different frequency than NTSC 3.57 MHz. -X1 can be swapped while console is running, system won’t crash, audio still works, but video won’t recover -If overclocking X1, might be best to alter the VI settings at the same time to try and take advantage of the faster video and audio signal (horizontal scan, etc). -Unless raising the voltage, the clock generators on the N64 won’t reach a VCLK over 94 MHz – at this frequency the video output appears as such below. X2 [System Clock] -Clocks and synchronizes RDRAM, RCP (MClock: MasterClock of CPU), PIF, and CIC. -Overclocking X2 increases the speed of the entire console, minus the video and audio circuits. -X2 above 15.0 MHz causes a video corruption (video lines seem to shift right), can be corrected by overclocking X1 at the same time, i.e. raising video bandwidth. -Maximum limit for X2 is a 20.5 MHz crystal (lots of modification), it seems the PIF might be having issues and locks the console. Above 19.0 MHz, a number of games stop outputting video, but sound and game still continue running. -The highest clockable memory chip is the RDRAM36-NUS CPU Overclock (R43xx CPU) -CPU gets its clock from RCP’s MasterClock (MClock), and multiplies it accordingly to what the DivMode settings are set at. Each DivMode setting can work with a certain range of MClock frequencies, 187.5 MHz is impossible to reach at 3.0x, but an MClock of 41.7 MHz will work at 3.0x to generate 125 MHz (this seems to be about the limit on N64 CPU). DivMode of 1.0x can still work up to about 90 MHz. -As far as a CPU-only overclock goes, success and stability probably lies in a number of factors: decoupling and bypassing capacitor integrity/quality, CPU voltage, and noise on power rails (fan installed on 3.3V line). -I won’t argue which CPU revision can handle a higher clock, but I have had more success in the Non CPU-A chip in running consoles at 2.0x setting. -Moving the CPU multiplier up can mess up the cadence of certain games (more CPU cycles made available over a 1 second period), overclocking with a crystal swap will have the same effect - it would be interesting to feed the CPU its own clock source locked at 62.5 MHz, while everything else (RCP) runs at a faster clock than 62.5 MHz.