Errors at first, then no errors for 29 passes

[ceevee]

I ran MemTest86 v7.4 on one 8 GB stick DDR3.

First round gave 1 error in test 7 on the 11th pass. Second round gave 2 errors in test 6 on the 2nd pass. Third round gave no errors after 29 passes (only test with HTML saved).

Afterwards, I also ran a windows based RAM test (HCI) overnight which gave no errors after 1500% coverage.


Can anyone provide an opinion on these results? Is the RAM stick bad?


HTML file: Summary

Report Date	2018-01-30 18:08:35
Generated by	MemTest86 V7.4 Free (64-bit)
Result	PASS

System Information

EFI Specifications	2.31
System
Manufacturer	Hewlett-Packard
Product Name	HP Compaq Pro 6300 SFF
Version
Serial Number	removed
BIOS
Vendor	Hewlett-Packard
Version	K01 v02.90
Release Date	07/16/2013
Baseboard
Manufacturer	Hewlett-Packard
Product Name	339A
Version
Serial Number	removed
CPU Type	Intel Core i5-3470 @ 3.20GHz
CPU Clock	3193 MHz [Turbo: 3591.9 MHz]
# Logical Processors	4
L1 Cache	4 x 64K (92607 MB/s)
L2 Cache	4 x 256K (48882 MB/s)
L3 Cache	6144K (28726 MB/s)
Memory	8071M (9816 MB/s)
DIMM Slot #0	8GB DDR3 PC3-12800
	Patriot Memory (PDP Systems) / PSD38G16002
	11-11-11-28 / 1600 MHz / 1.5V

Result summary

Test Start Time	2018-01-29 18:48:48
Elapsed Time	23:19:40
Memory Range Tested	0x0 - 21EE00000 (8686MB)
CPU Selection Mode	Parallel (All CPUs)
ECC Polling	Enabled
# Tests Passed	353/353 (100%)

Test	# Tests Passed	Errors
Test 0 [Address test, walking ones, 1 CPU]	30/30 (100%)	0
Test 1 [Address test, own address, 1 CPU]	30/30 (100%)	0
Test 2 [Address test, own address]	30/30 (100%)	0
Test 3 [Moving inversions, ones & zeroes]	30/30 (100%)	0
Test 4 [Moving inversions, 8-bit pattern]	30/30 (100%)	0
Test 5 [Moving inversions, random pattern]	29/29 (100%)	0
Test 6 [Block move, 64-byte blocks]	29/29 (100%)	0
Test 7 [Moving inversions, 32-bit pattern]	29/29 (100%)	0
Test 8 [Random number sequence]	29/29 (100%)	0
Test 9 [Modulo 20, ones & zeros]	29/29 (100%)	0
Test 10 [Bit fade test, 2 patterns, 1 CPU]	29/29 (100%)	0
Test 13 [Hammer test]	29/29 (100%)	0

[David (PassMark)]

Yes, very likely RAM is intermittently bad.

[ceevee]

Changed the motherboard, CPU, PSU and also installed other RAM sticks [4+4+8+8]. The 8 GB DDR3 ram stick I tested in the original post is paired in the same channel with the other RAM stick that was originally included in the 16 GB kit (2x8GB). The two 4 GB sticks are from another manufacturer. Previously, I've tested these other sticks (the other 8 GB stick and the two 4 GB sticks) in memtest in this changed motherboard and they all passed (11 passes).

First I ran HCI memtest to 600% coverage with no errors. Then I ran two other tests with no error but only extremely briefly (1 hr AIDA64 memory/cache stress and 6 hours prime95 custom config FFT size, no FFT in place, & 95% RAM).

Lastly, I ran memtest86 7.4 with no error on 10 passes (below). There were row hammer notes, though.

Summary

Report Date	2018-02-02 18:43:50
Generated by	MemTest86 V7.4 Free (64-bit)
Result	PASS

System Information

EFI Specifications	2.31
System
Manufacturer	ASUS
Product Name	All Series
Version	System Version
Serial Number	System Serial Number
BIOS
Vendor	American Megatrends Inc.
Version	2201
Release Date	06/25/2015
Baseboard
Manufacturer	ASUSTeK COMPUTER INC.
Product Name	B85M-G R2.0
Version	Rev X.0x
Serial Number	removed
CPU Type	Intel Core i7-4770 @ 3.40GHz
CPU Clock	3392 MHz [Turbo: 3691.4 MHz]
# Logical Processors	8 (4 enabled for testing)
L1 Cache	4 x 64K (175221 MB/s)
L2 Cache	4 x 256K (52675 MB/s)
L3 Cache	8192K (39189 MB/s)
Memory	24503M (16237 MB/s)
DIMM Slot #0	4GB DDR3 XMP PC3-12800
	Team Group Inc. / Vulcan-1600
	9-9-9-24 / 1600 MHz / 1.500V
DIMM Slot #1	4GB DDR3 XMP PC3-12800
	Team Group Inc. / Vulcan-1600
	9-9-9-24 / 1600 MHz / 1.500V
DIMM Slot #2	8GB DDR3 PC3-12800
	Patriot Memory (PDP Systems) / PSD38G16002
	11-11-11-28 / 1600 MHz / 1.5V
DIMM Slot #3	8GB DDR3 PC3-12800
	Patriot Memory (PDP Systems) / PSD38G16002
	11-11-11-28 / 1600 MHz / 1.5V

Result summary

Test Start Time	2018-02-01 22:30:48
Elapsed Time	20:12:57
Memory Range Tested	0x0 - 61E000000 (25056MB)
CPU Selection Mode	Parallel (All CPUs)
ECC Polling	Enabled
# Tests Passed	130/130 (100%)

Test	# Tests Passed	Errors
Test 0 [Address test, walking ones, 1 CPU]	11/11 (100%)	0
Test 1 [Address test, own address, 1 CPU]	11/11 (100%)	0
Test 2 [Address test, own address]	11/11 (100%)	0
Test 3 [Moving inversions, ones & zeroes]	11/11 (100%)	0
Test 4 [Moving inversions, 8-bit pattern]	11/11 (100%)	0
Test 5 [Moving inversions, random pattern]	11/11 (100%)	0
Test 6 [Block move, 64-byte blocks]	11/11 (100%)	0
Test 7 [Moving inversions, 32-bit pattern]	11/11 (100%)	0
Test 8 [Random number sequence]	11/11 (100%)	0
Test 9 [Modulo 20, ones & zeros]	11/11 (100%)	0
Test 10 [Bit fade test, 2 patterns, 1 CPU]	10/10 (100%)	0
Test 13 [Hammer test]	10/10 (100%)	0

Test 13 [Hammer test] Warning

Note: Your RAM may be vulnerable to high frequency row hammer bit flips. However the conditions needed to induce these errors occur only very rarely in normal PC usage, and so this should not be of concern to most users.

It looks okay for now, but I will consider replacing the 8GB stick at a later time.