I recently upgraded my macbook from 4G to 8G and wonder if there's a tool to test the quality of new memory.
memtest 4.22 seems only test about 1G:
$ memtest all 2 Memtest version 4.22 (64-bit) Copyright (C) 2004 Charles Cazabon Copyright (C) 2004-2008 Tony Scaminaci (Macintosh port) Licensed under the GNU General Public License version 2 only Mac OS X 10.9 (13A603) running in multiuser mode Memory Page Size: 4096 System has 4 Intel core(s) with SSE Requested memory: 1048MB (1099390976 bytes) Available memory: 1048MB (1099390976 bytes) Allocated memory: 1048MB (1099390976 bytes) at local address 0x0000000101000000 Attempting memory lock... locked successfully Partitioning memory into 2 comparison buffers... Buffer A: 524MB (549695488 bytes) starts at local address 0x0000000101000000 Buffer B: 524MB (549695488 bytes) starts at local address 0x0000000121c3b000
I reboot into single user mode as described in this question, and test again. Works better, about 7G memory tested. So I guess the missing 1G is reserved for the graphics card?