Errors outside of RAM address range

[Puzzled]

Every month or two I get an error message on my HTPC. It usually varies slightly but always seems to come back to an unexpected shutdown per the Events Logs. Unfortunately it never says what caused the unexpected shutdown.

I have 2 sticks of 2GB RAM and 2 mobo slots. If both sticks are used, no matter which one in which slot, Mentest86 shows a lot of errors.

Memtest86 usually shows Lowest Address of 4720.2MB, but once it displayed 4844.2MB.
It always shows Highest Address of 4844.2MB.

If I use only a single stick in either slot, no errors are shown.

IOW 2 sticks always have errors and 1 stick never has an error.

What could Memtest86 be showing as an error that has an address higher than the amount of memory that I have?

Is Memtest86 really testing an address that is not within the RAM range? If so then why doesn't it test the same address when only RAM stick is used?

Any suggestions, ideas or recommendations would be greatly appreciated.
Thanks

Windows 7 64 bit, Intel G620 CPU, ECS mobo, 4GB RAM, 1.5TB Seagate Green HDd, two AverMedia Duet tuner cards.

[David (PassMark)]

I assume you are using MemTest86 V4.3 or V5 and not some older release?

Would have been good to see a photo of the screen showing the errors.

It is certainly possible to get an address slightly above the amount of RAM installed. BIOS can make holes in the address space to 'map' in other devices. So the address space won't be continuous.

Technically it is possible to only have errors with both sticks. For example with 1 stick installed you'll never get into dual channel mode.

Can you borrow a set of replacement RAM (2 x 2GB, or 2 x 4GB) to try out.

[Puzzled]

Yes I was using V4.3.
I did take a photo of the screen & am including here.
I do have another 2GB x 2 set of RAM. I have not tried that yet because they are in my main desktop. I'll try to take things apart & try them this weekend.

If BIOS is using the address in question, is there a way to find out what it's being use for, such as the HDD or a tuner card? I search for info on how to do that but came up empty handed.

[Puzzled]

This is the G.SKILL RAM that gives me errors in PC#1.
http://www.gskill.com/en/product/f3-10666cl9d-4gbns

I pulled this Micron RAM out of my other computer, PC#2. It appears to have the same specs as the problematic RAM.
http://www.micron.com/parts/modules/ddr3-sdram/mt8jtf25664az-1g4

The Micron RAM passes Memtest86 when using both sticks in PC#1, no matter which one is in which slot.

I tried the G.SKILL RAM in PC#2 and Memtest does not show any errors no matter which one is in which slot.

IOW Micron works in both PCs.
G.SKILL works in PC #2 but not in PC#1.

Obviously there is a problem using the G.SKILL RAM in PC#1. Would you suspect it is a RAM problem or a motherboard/BIOS problem?

[David (PassMark)]

It does happen that you can get compatibility issues. The same RAM can work in one machine, but not another. Can be very hard to track down the true cause however. Could be a noisy power supply, EMI, dirty connectors, timing issues, temperature / cooling related, etc..

If you now have both PC passing the test, then I would leave it this way, and see how it runs in Windows.