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I'm getting recent memory test failures in an HP Pavilion g7-1303sa laptop (one month out of warranty :( ). The memory is the factory installed 6GB installed as a 2GG module in the top slot and 4GB in the bottom slot (nearest the access panel). There are only two slots. I've tested with both the built in HP diagnostics and the memtest boot utility and both show failures (actually memtest86+, I think). The HP specs list the max system memory as 6GB but some other sources list it as 8GB.

What's puzzling me is that if I test either of the modules individually in either slot they work absolutely fine even after running a full memtest cycle for a few hours. If I install both modules either way round I get immediate memory test failures.

memtest reports the system memory as being something like 5.5GB which is presumably because the GPU is taking some of that memory for its own use. I can't see any options in the BIOS configuration for changing GPU memory usage. However interestingly memtest reports the error addresses around the 5.6GB - 5.7GB range - bigger than the reported memory and presumably within the area used by the built in GPU if my vague theory is correct.

The manufacturer specs lists the GPU as:

Graphics AMD Radeon HD 6520G Discrete-Class (up to 2.98 GB total memory)

Is this some sort of memory failure, a GPU misconfiguration or failure or is it possible that I could fix it by replacing one or both of the memory modules? If I just workaround the problem by installing only the 4GB module is it likely to be a permanent fix or is the motherboard about to die in some way?

EDIT:

Additional information from the service and maintenance manual:

  • 2 customer-accessible/upgradable memory
  • Supports dual-channel memory
  • Supports up to 8192 MB of system RAM DDR3/1333 MHz (DDR3-1600 (1 GB / 2 GB / 4 GB / 8 GB) memory modules supported as an alternative source for DDR3-1333)

So it sounds like I might be able to use a single 8GB module instead if all else fails.

Hennes
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persiflage
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    What is the exact spec of the two memory sticks and the motherboard? They could be incompatible; there might me a requirement that they work in pairs (and yours are different sizes); or you might be having electrical problems, typical of motherboards or power supplies that are about to die - the current is enough for one, but not enough for two. – pgr Jan 21 '15 at 17:09
  • Don't have them handy to look at now but they are DDR3 and they are the original factory installed memory - I did notice they were made by different manufacturers though. There doesn't seem to be a requirement that they are in matching pairs. HP list the maximum memory as 6GB - 4+2. Perhaps the next step is to try an alternative laptop power supply - I have a general purpose spare. – persiflage Jan 21 '15 at 17:14
  • HP don't list motherboard details in the official documentation. Not sure if the motherboard manufacturer and model number are visible from the access hatch. – persiflage Jan 21 '15 at 17:30
  • This answer seems to explain why the error addresses are larger than the reported memory capacity http://superuser.com/questions/419496/why-are-the-failing-addresses-in-memtest86-higher-than-my-total-memory – persiflage Jan 21 '15 at 17:32
  • You COULD read the specs such as; you can at most get 6GB USER memory, e.g. 2GB of 8GB gets reserved for graphics. I find 6GB to be an odd limit with regard to usual hardware limits. Memory errors MAY be due to oxidized pins in the RAM sockets or on the modules, I have occasionally had success in fixing similar trouble by removing SIMM's and running a pencil eraser along the pins (keep the touch light enough to not cause damage), then running without trouble again after putting them back. – Hannu Jan 21 '15 at 19:00
  • Thanks for the feedback, Hannu. I will try the eraser suggestion gently. Which specs are you referring to? The HP product specifications link I gave simply lists maximum RAM as 6GB and graphics as up to 2.98GB which I mentioned in my original question. Other web sites including RAM vendors who guarantee compatibility refer to a maximum of either 6GB or 8GB. It's not clear to me which are correct. I agree that 8GB seems like a peculiar limit. I'm still not clear what the relationship is between system RAM and GPU RAM on this system. – persiflage Jan 22 '15 at 15:52

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