I have recently had two quad cored AMD A6 boxes with AMD A55 chipset and AMD Radeon HD6530D integrated graphics on a Gigabyte motherboard fail Memtest86+ v4.20 memory testing.
8Gbyte of DDR3 memory comprising two sticks and in both systems the memory was reported failing at a wall time of approx 21min 24sec and pass 43%, test 0%, test #7 [random number sequence].
The memory sticks were swapped over with the same result. One stick was removed and the remaining one tested in both slots with the same result and the second stick of memory behaved in the same manner, The wall time at first failure with single sticks was in the order of 9min 52sec, but the identical test failures occurred. The memory address of first failures was not noted except in one case where it was 135.0Mbyre.
The source of Memtest86+ v4.20 was variously SUSE 12.2 64 bit, SUSE 12.1 64 bit and SUSE 12.2 32 BIT iso direct downloads from OpenSUSE.org to DVD. Each failed in the same manner and a firmware test on the same distro disk gave several MTRR errors which I didn't record. The distros appeared not to get to the first base when selecting the install option. There being no live CD option.
Interestingly a download of Fedora 17 appeared to work and the Memtest86+ facility on that disk ran successfully overnight and the Live CD appeared to be function happily as far as I was able to check it out.
A standalone copy of Memtest86+ iso downloaded and cut to CD ran fine on a the AMD Sempron system where it was downloaded and cut to CD, but appeared not to want to boot successfully on the target AMD A6 system.
Does anyone have any clues as to why Memtest86+ is behaving in this manner and why they are not all borne equal when it comes to testing this system? Both systems were rejected as faulty back to the vendor, who was happy to confirm that the first one was indeed faulty. I am awaiting their received wisdom on the second one. I am very aware that the system is not unduly expensive and the vendor has stood the carriage bill for two systems in two directions already.