Error Testing Four DIMMs Simultaneously but Not One, Two, or Three

[busthead]

Hello, I have a HP Compaq 6000 Pro Microtower with a 531965-001 system board. I'm using G.SKILL F3-10600CL9D-8GBNT RAM. Testing one, two, or three DIMMs simultaneously with MemTest86 results in no errors. Only when I add a fourth DIMM does MemTest86 find errors.

Is this result an indicator of a bad system board, power supply, or something else entirely?

If this is not the appropriate forum, please advise.

Thx

[David (PassMark)]

RAM errors normally indicate bad RAM. So I would initially suspect the RAM is bad. This is way more likely than a bad power supply.

[busthead]

Understood, but why do the RAM errors only manifest when the fourth slot is populated?

How do I identify which DIMM is bad when MemTest86 produces errors?

[David (PassMark)]

Maybe the RAM stick in the forth slot is bad.

See also,
https://www.memtest86.com/troubleshooting.htm

[busthead]

I have numbered my DIMMs and tried every possible combination/order, including testing each stick one at a time. Errors are only detected when a DIMM is installed in the fourth slot - regardless of the DIMM.

[David (PassMark)]

I find it a bit hard to believe that the errors are the same regardless of the stick in use.

Maybe when the 4th slot is in use the extra power requirement causes a slight voltage drop. Or maybe the 4th slot has a marginal / intermittent connector.

[busthead]

I never said "the errors are the same." I said, "Errors are only detected when a DIMM is installed in the fourth slot - regardless of the DIMM."

I haven't documented the type or magnitude of the errors. Should I? If a voltage drop or intermittent connection did occur, is there a particular error type that would be expected?

[David (PassMark)]

According to Intels's docs that chipset only supported 1-Gb, 512-Mb DDR3 sticks.
https://www.intel.com/content/dam/ww...-datasheet.pdf

The HP manual says, 512MB, 1GB, and 2GB technologies are supported.
http://h10032.www1.hp.com/ctg/Manual/c01870856

They also say that 16GB is supported, but I am not sure how if you have 4 slots with 2GB each, that is only 8GB. Other pages also claim 4GB sticks can work, so who knows. But maybe you are pushing the limits of this old motherboard.

[busthead]

It appears to always be test 6 that produces the error and only in a single bit.

Is this error significant enough to be concerned about or will CRC or other protections prevent this error from causing system issues?

Also, Is it possible to only run test 6 repeatedly?

Thx

[David (PassMark)]

For RAM there is no CRC and "other protections". (Unless you have ECC RAM, which you don't).

You can pick which test to run from the main menu.

Ignore it if you want. The whole machine is only worth maybe $50 now. In a faulty state maybe $10. So hard to justify spending much time on it.

[busthead]

Is this error significant enough to be concerned about...will it cause system issues?

i.e. what is the likelihood that test 6 detecting a error in a single bit will affect the system?

[David (PassMark)]

Its just random. Impossible to guess at what that particular memory address will be used for.

Might never be used and never cause a problem.
Might be used for disk cache and corrupt every file written to your hard drive.