07-19-2020, 08:09 PM
The wiki says we can use either the thermal pad or thermal paste between the heat sink and the rk3399. However, the RAM chips and SoC have different heights, so using the usual thin layer of paste would leave the RAM unprotected. (Worse than that, actually, since the heat sink would block airflow across the RAM surface.)
This leads me to a few questions:
1. What exactly is the height difference between the RAM and SoC? Is a mechanical diagram available? (This would tell us the thickness required for copper shims to compensate for the difference.)
2. If we were to cut the thermal pad (included with 30mm heat sink) into smaller pieces for use on the RAM chips, and then apply a very thin layer of paste to the SoC (with no pad), would the pads on the RAM prevent the heat sink from sitting flush against the SoC + paste?
3. Thomas Kaiser (tkaiser of Armbian) mentions in this post the risk of a short when using the heat sink with thermal paste alone, but the picture he refers to is no longer available. What contacts might short in this scenario?
4. Can the DRAM ever get hot enough to require a heat sink? (Maybe it doesn't need cooling?) If so, what sort of load causes it to get that hot?
This leads me to a few questions:
1. What exactly is the height difference between the RAM and SoC? Is a mechanical diagram available? (This would tell us the thickness required for copper shims to compensate for the difference.)
2. If we were to cut the thermal pad (included with 30mm heat sink) into smaller pieces for use on the RAM chips, and then apply a very thin layer of paste to the SoC (with no pad), would the pads on the RAM prevent the heat sink from sitting flush against the SoC + paste?
3. Thomas Kaiser (tkaiser of Armbian) mentions in this post the risk of a short when using the heat sink with thermal paste alone, but the picture he refers to is no longer available. What contacts might short in this scenario?
4. Can the DRAM ever get hot enough to require a heat sink? (Maybe it doesn't need cooling?) If so, what sort of load causes it to get that hot?