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SMC has engineered an entirely new VRAM SIMM for vintage Macs. This new, low latency 60ns design allows you to take CPU overclocking to an all new level!


Version history

Rev V.1.0(2022/02/04): Alexandre Marcoux redesigned it into two layers based on Zane Kaminski's original design. Drake added artwork to it and we ended up selling it.


Rev V.1.1(2024/03/20): Since the specifications were not suitable for mass production, we went back to original design and redesigned it. redesigned by Kay Koba.

- Reinforced +5V lines.

- Capacitors with little individual difference, a very small ESR and ESL values, suitable for high frequencies.

- New foot prints.


Special thanks to Zane Kaminski and Alexandre Marcoux for early work.



-2pcs per set

-VRAM capacity: 512KB (1024KB for 2pcs)
- SIMM socket type: 68-pin

- Speed: 60Ns

-Guaranteed CPU overclock: 49Mhz*

* Theoretically, the CPU overclock limit is 55Mhz with SMC-VRAM, but the actual limit varies by machine specifications. High CPU clock speeds are also contingent on the use of extremely low ESR capacitors on the motherboard. Before shipping, we will test VRAM at 50Mhz.

-Appearance: Blue LEDs are installed.


Compatible Macs

LC475, LC575 (Mystic), Quadra650 (AKA Centris650), Quadra 800 / 840AV and more.



-Although this VRAM can be used on 68030 machines without problem, this is a high performance VRAM-SIMM that is best for super high overclocking. Recommended VRAM for use with Spicy O'Clock (sold separately).

-If the spring of the terminal of the VRAM socket does not return due to deterioration over 30 years, tension may not be applied to the contacts of the VRAM card and contact failure may occur. In this case, it is usually solved by lightly pushing the card several times in the direction of the spring, but in rare cases, the contact failure may not be solved. SMC-VRAM is 1.2mm, but Apple's genuine VRAM is 1.26mm, which is a symptom caused by the thickness of PCB being about 0.06mm. Of course, there is no problem if the socket is not deteriorated.

-The blue LED on the VRAM card indicates that + 5V is energizing the card, but it is not an LED to signal operation.

SMC VRAM 512KB 60Ns for 68040 Overclocking/ 2 pcs per set

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