Execution Time for 16GB DDR

[Aaron]

I want to test for defective RAM similar to Memtest86.

What are the recommended parameters and minimum execution time for 16GB of DDR4 RAM on a consumer laptop? Stressapptest defaults to using 4 threads. 

[Nick Sanders]

A 120s runtime will catch most errors, and the default threads and memory size are normally fine. You can also run for several hours to find very intermittent issues.

[Aaron]

I appreciate that information. I have been using memtester (https://github.com/jnavila/memtester) and to test 16GB it can take from about 40 mins to an 1 hour. 

Do you know what the differences are between memtester and stressapptest and if one is better than the other in certain situations?

[Nick Sanders]

stressapptest was developed as a more efficient alternative to memtester. It runs a number of threads with randomized transactions with the intention to get the most test coverage in the least amount of time, and is tunable in terms of time spent testing.

memtester sequentially runs a series of patterns, each designed to find specific problems, and can't easily adjust runtime. 

Generally, stressapptest is better at finding errors faster than memtester, finding errors that aren't specifically targeted by memtester, finding stress related errors, and finding intermittent errors. memtester has certain types of patterns that can bring out specific DRAM fault types that aren't well covered by stressapptest. So for best validation, you should run both, for some number of hours each. If you are in a situation where you have limited time, like a manufacturing line, a short stressapptest run is a way to have reasonable confidence memory is reliable. 

[Aaron]

Makes sense, thank you. With 120s in stressapptest catching most errors should the duration of the test scale with the size of the memory being tested? For example, should 32GB of consumer memory also be tested for 120s, or should it be around 240s minimum?

[Nick Sanders]

It's just a ballpark number, you can check the bytes per second copied on the "Completed" line relative to the amount of memory tested to get an approximate of how many times each memory location is checked during the test. It should be at least a few accesses per location. 

For comparison, memtester has ~20 subtests where each test checks each memory location one to a small constant number of times per run.

If this is just your own computer and you have reason to suspect your DRAM, like it was discounted, or you overclocked it, it's probably best to run both for a few hours each.