AD9866 Heatsink - softerhardware/Hermes-Lite2 GitHub Wiki
The AD9866 may run hot in some builds of the Hermes-Lite 2. There are small heat sinks such as this or this which may be used to help cool the AD9866. The size of the AD9866 is 9mm by 9mm, so care must be taken to not short pins if any heat sink that size or larger is used.
There are heatsink sets commonly sold for the Raspberry Pi which works well with the Hermes-Lite 2.0:
If any of the links above are broken, just search for "Raspberry Pi heatsink." The set usually comes with two 9X9mm and one 14x14mm heatsink. Use the smaller heatsinks on U7 and U4. Use the larger heatsink on U2.