# Memory Test

The Memory test, tests the reliability of the RAM installed in the computer. As BurnInTest runs within windows some of the available RAM is being used by windows and any other applications running. Any memory that is not already in active use will be grabbed by the Memory test.

The memory test works by writing a pattern numbers in the RAM, then verifying the numbers read from the RAM match this sequence. The pattern used will change automatically from one cycle to the next. Possible patterns are,

Sequence (0,1,2...255)

Binary 1 (10101010)

Binary 2 (01010101)

Zeros (00000000)

Ones (11111111)

The Test pattern may be selected to be one of the above, or to cycle through each of the above in the above order.

There are 3 sequences that the test goes through,

1/Memory allocation. The test will dynamically grab and release memory depending on how much is currently available. The amount that has been grabbed and is under test is displayed in the Test Ram Field.

2/Writing the number sequence.

3/Verifying the number sequence.

The total amount of free RAM is displayed in the Memory Test Window. This number should always be bigger than the Test Ram number. Some memory is always left available to avoid Out of Memory Errors, and disk thrashing caused by Windows swapping to disk.

For the Memory test a cycle is defined to be the number of times the above 3 step sequence is completed. The ‘operations’ count represents the number of bytes read or written.

It should be noted that not all RAM faults will be detected by this test. This is especially the case if Windows or the Windows cache is using a large proportion of the available RAM. RAM faults may show up as system crashes or disk errors however.

Standard memory test

The standard memory is the normal test for testing memory. See the description in the RAM test preferences window for more details.

Torture test (Memory over-allocation & disk swapping test)

The torture test is a multi-process memory test. Multiple processes are started in their own virtual address space and each process allocates and tests a block of RAM. This avoids the problem of virtual memory fragmentation which the standard test can experience trying to allocate a single large block of RAM. Each process runs asynchronously, so writing and reading of various memory blocks will take place at the same time in different processes. The other advantage over the standard test is the possibility to over-allocate the RAM. (The standard test attempts to prevent this to avoid disk swapping). Over-allocation takes place when more RAM is used by the torture test than is currently available in the system. This then results in Windows disk swapping memory blocks into a paging file on the disk. This continual swapping to and from the disk places a very heavy load on the system. The I/O activity on the disk will increase dramatically but CPU load can actually decrease as more and more time is spent waiting for the paging activity to complete. Depending on the level of over-allocation Windows may need to extend the paging file or may even fail as it runs out of available RAM.

Addressing Windows Extension (AWE) memory test

The Addressing Windows Extension (AWE) memory test allows a larger area of memory to be tested on 32-bit versions of Windows. It requires some additional administrator user rights. It will also only work in Window 2000 and XP. See the description in the RAM test preferences window for more details. The advanced memory test is only available in the Professional version of the software.

BurnInTest 64bit version specific:

The AWE memory test is not available under 64bit Windows. However, the standard test will test very large memory sizes under 64bit Windows.

End 64bit specific

See also

RAM test preferences

Setting administrator user rights