I have two questions: 1. When Windows 7 Memory Diagnostics Tool runs what portion (size in Mb) of RAM is not tested due to occupancy by whatever minimized OS is used to boot up the system and the running app itself? 2. On 64-bit Vista or Windows 7 is the Memory Diagnostics Tool a 64-bit app or a 32-bit app running on a 64-bit operating system? Or put a different way, does it test RAM beyond the approximate 3.2Gb barrier?

1. The entire memory range is tested. I don't know how this is written internally, but it definitely doesn't leave out a patch where it is loaded! 2. The memory test is a 32 bit application, and will only test up to 4GB of RAM. Memory above that will not be tested. PS: Please note: The 32 memory 'barrier' is 4GB, not 3.2GB. This is a common misconception. The remaining 0.8GB is often (but not always completely) use by device drivers.

Thank you very much for the reply. I have a very hard time believing #1, and should have realized #2, but since both answers have been signed off on by MS staff I will accept both. Again, thank you very much. That clears up a lot of questions for me and I hope others. Powell, aka FNFreedom's the Answer! What's the Question?

Thank you very much for the reply. I have a very hard time believing #1, and should have realized #2, but since both answers have been signed off on by MS staff I will accept both. Again, thank you very much. That clears up a lot of questions for me and I hope others. Powell, aka FNFreedom's the Answer! What's the Question?

Is there another application available to test above 4GB? like an actual 64bit supported application? now 1/3rd of my memory cannot be tested and ruled out as a possible problem area. thanks in advance, leo

Memtest86 4.0 [not to be confused with memtest86+] is a 64-bit app. that will test up to 64Gb of RAM. The server version to 8Tb. Freedom's the Answer! What's the Question?

So to continue this thread, and I am not trying to embarrass anyone at MS, but will the MS Mem Diag app included with a pretty decent Win8 OS be 64-bit? I mean, low cost 8Gb sticks are becoming prevalent.Freedom's the Answer! What's the Question?