Official GIGABYTE Forum
Questions about GIGABYTE products => Motherboards with AMD processors => Topic started by: MrPete on January 03, 2011, 09:19:15 pm
-
Hi all.
My configuration is at the bottom for reference.
I have just solved a painful long-term issue. Seems to me it did not have to be so painful, if only I had a bit more information.
The issue I found, and how I solved it, may be helpful to others.
My big question: if a GigaByte BIOS is generating invalid memory layout information (e820), what indication is there in the BIOS version update notes to tell me that a BIOS update will fix memory access problems?
ANSWER: None. Read the following. Perhaps you have a BIOS bug too!
Background
My system (MA78GM-S2H rev 1.0, BIOS rev F4 -- fully supports my Athlon 64 x2 5400+ cpu) has always worked perfectly (Vista 32) but also has always had strange problems with Memtest86+ -- with 4G of RAM installed, memtest would crash a few seconds after starting, unless I immediately reconfigure it to reduce the ending address.
I ignored this for a long time, since I could test each memory stick one at a time without any trouble, and the system itself worked fine.
But... now I wanted to upgrade to Win7 x64. And the upgrade tool consistently crashed (BSOD x24 and x50). Nothing that directly points to RAM, but I figured I had better ensure every part of my system is running perfectly.
I went back to the latest memtest86+. It is claimed to work correctly with very large amounts of RAM (64GB and more). My little 4GB is nothing! So... why was I having so much trouble?
What I could see:
- With 2G installed (1 stick), no trouble at all. Test range was reasonable.
- With 4G installed (2 sticks), ALWAYS immediate trouble no matter what brand of RAM, no matter where installed, no matter what BIOS settings.
[Symptoms: 2 seconds after booting Memtest86+ 4.20beta or any earlier version, I get black "spots" on the screen, and a couple of seconds later, the screen is replaced by big swaths of color (big red, yellow and green bar, IIRC) ]
With more testing and careful sleuthing:
- The 4G "upper limit" is ridiculously high (up above 4.7G!)
- MemTest86 uses a standard for retrieving the BIOS memory map, called "e820"
- Changing the shared video memory size (128MB-512MB) has no effect on the upper limit or available memory size. That sounds wrong.
- Tried the Win7 upgrade with only 2G installed. It works!
At this point, I was very suspicious that my BIOS was incorrectly reporting the e820 memory map. Unfortunately, I got stuck, as I can't find any tools for listing or diagnosing the e820 memory map.
So I looked through the Gigabyte BIOS update list....
What Gigabyte Tells Us
Looking here: http://www.gigabyte.us/products/product-page.aspx?pid=2758&dl=1#bios (http://www.gigabyte.us/products/product-page.aspx?pid=2758&dl=1#bios) we see...
All of the BIOS updates after F4 appear to be for new CPU support. They all are about either
* New CPU ID support
* New rev of AGESA code for a new CPU
None of this says anything about e820 or memory maps or trouble running with 4G RAM.
I took a risk and updates my BIOS to the latest (beta), F12B.
Everything Works Perfectly Now.
SO: there was a BIOS bug causing the RAM memory map to be reported incorrectly. The symptoms:
* MemTest86+ crashed on load, and/or soon thereafter, but only if more than 2G of RAM was installed
* Windows 7 x64 (Home Premium) would not install, getting BSOD stop codes 0x24 (hard drive) and 0x50 (video) errors
That seems pretty significant to me.
What am I missing? Should I have been able to figure this out?
-
Hi and welcome to the Gigabyte Forum.
My configuration is at the bottom for reference.
I'm afraid that you forgot to include your system specs.
My big question: if a GigaByte BIOS is generating invalid memory layout information (e820), what indication is there in the BIOS version update notes to tell me that a BIOS update will fix memory access problems?
None. It is a problem we have long been griping about but to no avail. The description of motherboard BIOS updates is short to the point of being practically useless. Most manufacturers are a bit lax on this front but Gigabyte do seem to be particularly lacking.
Thanks for the information anyway as it might well help other people in the future.
-
Whoops! Sorry.
MA78GM-S2H rev 1.0 originally BIOS F4 now F12B
4GB RAM (2 sticks), have used both Patriot and G-Skill 1066
Athlon 64 x2 Dual Core 5400+ CPU
(Wide variety of disk drives, etc.)
Currently running video at 700MHz, CPU at 12.5x230, stock voltage.
-
One more note:
I see a number of places where people recommend testing RAM only one stick at a time.
That's a good idea if you suspect RAM trouble.
HOWEVER... once you've done a basic test like that, if your system can't properly handle Memtest86+ with a full complement of RAM, it is time to suspect that your BIOS has this bug... and if no update is available, it is time to poke at Gigabyte to fix the "e820 memory map" in your BIOS for your CPU / memory configuration.
Perhaps some day a smart person will write an e820 "dump" app...