On Thursday 29 Jan 2015 22:13:28 Volker Armin Hemmann wrote: > Am 28.01.2015 um 00:28 schrieb walt: > > Yesterday I installed 4GB more of RAM in this machine for a total of 8GB, > > and the machine soon began random segfaulting and even a kernel crash or > > two, so obviously I suspected the new RAM was faulty. > > > > I let memtest86+ run overnight and it found zero memory errors. Today I > > exchanged the new RAM anyway and got a different brand this time, and > > that fixed the problem. > > > > My question is why didn't memtest86+ find any errors? Could it be that > > the first RAM I bought was actually okay but this machine didn't like it > > for some reason? Both were DDR3/1333MHz, just from different > > manufacturers. > > Since this was not mentioned yet: > > Maybe because the ram was not faulty at all. > > Maybe it really operated in the range of allowed tolerances - and those > were never crossed with memtest as a very light system load. > > But with an OS booted, the CPU, graphics solution, harddisks all sucking > power like mad, your mainboard or PSU might not be able to deliver as > stable currents as the specifications demand. Some memory is more > tolerant than other.
Yes, I've witnessed this too after adding 2 new memory modules of a different size to the originals and from a different manufacturer, in a box with a suspect PSU. Memtest+86 was not erroring out, but the system was crashing when put under pressure. Typically I would get errors when more than the size of the old memory started being used. This got worse over time, as the PSU components were ageing. Eventually I replaced a capacitor in the PSU and the memory problems disappeared. It has been already mentioned, but it is worth noting that some BIOS/MoBos are more sensitive to different brands of memory. In those cases I found that using the same make and size modules resolves the problems. -- Regards, Mick
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