Most people don’t really think about overclocking a Raspberry Pi, but when you’re a true overclocker you want to try to overclock anything and everything that you own. So, when HWBot user from the Netherlands rsnubje and Hardware.Info resident overclocker decided he was going to go for a world record run, he did not kid around. In order to overclock the 700 Mhz CPU on the Broadcom BMC2835 ARM-based SoC at the heart of the Raspberry Pi, he resorted to two extreme overclocking measures.
In order to reach the 1.5 GHz clock, a 114% OC, the two things that he implemented were the use of an EVGA EPower board and a phase-change cooler. The EVGA EPower board is basically a special board that is designed for overclocking purposes only in order to add more power to a GPU or CPU by creating a whole set of VRMs to take in up to 400A of extra power from the power supply where it may not be possible otherwise.
Rsnubje’s EVGA EPower setup for the Raspberry Pi – Image Credit: Rsnubje
Now, having enough power is a good thing for overclocking, but the next obstacle is usually temperatures as overclocking the chip and pushing more power to it will result in higher temps. In order to get a more stable overclock and keep temperatures down to manageable levels, he implemented a phase-change cooling solution where he basically strapped the whole board to the end of his single-phase phase-change unit (usually used for high-end stable CPU OCs). He also said that he believes that with this setup he can go much higher than 1.5 GHz but there appears to be a hard lock at 1.5 GHz on the chip, which may either be a Broadcom or Raspberry Pi limitation. He’s currently looking for help to get the clocks even higher.
Rsnubje’s cooling setup for the Raspberry Pi – Image Credit: Rsnubje
While overclocking a Raspberry Pi to 1.5 Ghz isn’t really going to do anything in terms of functionality considering the plethora of other ARM SOCs, it does illustrate the flexibility of ARM SOCs when their formfactor limitations are removed. People really like the Raspberry Pi and its overall open-source nature, so overclocking it may encourage others to overclock theirs as well and possibly get some free performance out of their already cheap Raspberry Pi boards. Hopefully we’ll see some overclocks over 1.5 GHz soon, just so we can see how far Broadcom’s chip can really go…