These tests should at least run 20 minutes (better 30) to get the idea about worst case conditions (since we experience with the NEO that the whole PCB and all components starts to heat up -- I've been able to burn my fingers yesterday when I did some cpuburn-a7 tests afterwards).
BTW: Another more realistic approach to test the performance efficiency of a specific heatsink is to use cpuminer (a bitcoin miner that can use NEON instructions and knows a benchmark mode). Simply grab https://sourceforge.net/projects/cpuminer/files/pooler-cpuminer-2.4.5.tar.gz/download then untar it, chdir into cpuminer-2.4.5 directory and then:
sudo apt-get install libcurl4-gnutls-dev
./configure CFLAGS="-O3 -mfpu=neon"
make
./minerd --benchmark
But please don't be surprised that performance numbers reported will be lower compared to other H3 devices. NEO uses a single bank DRAM configuration and DRAM clockspeed is way lower than on all other H3 boards. Therefore performance will be lower anyway but using cpuminer's benchmark mode you might get the idea how different heatsink/cooling solutions 'perform'. But to be honest: NEO is not made for performance anyway so better use the heatsink as a simple matter of precaution and forget about benchmarking this tiny board at all
In case anyone wants to build a HPC cluster with NEOs (weird to say the least ). I prepared an archive some time ago to do reliability testing with Pine64 that contains already a script to collect cpuminer benchmark numbers and feeds them into RPi-Monitor template therefore the efficiency of the cooling approach in question can be measured/compared directly: http://linux-sunxi.org/User:Tkaiser#Reliability_testing_on_Pine64 (see the screenshot there to get the idea)
