crazyscot

My desktop has an Intel Core2 Duo of 2007 vintage, with an Intel DG965SS motherboard. For the past four years it has had 2Gb of main memory, which largely served me well. Today I finally got round to upgrading it; having checked what it would take I reckoned I would get one 2Gb stick for each of the two spare slots, seeing as they're only £24 each at WOC.

So I booted back to my desktop and it was great; things were much faster. But then I noticed that the memory usage meter only showed me as having 3.2Gb available.

"Huh?" quoth I. 3.2G is a well-known issue if you're running a 32-bit kernel which doesn't have PAE enabled (i.e. is limited to 4G; you lose the top 800M or so of the address space to motherboard and OS internals), or indeed if you're running 32-bit Windows. But on a 64-bit machine running a 64-bit kernel? Surely not.

Well, in amidst the noise of bootup log there was this wonderful(?!) line:

WARNING: BIOS bug: CPU MTRRs don't cover all of memory, losing 2752MB of RAM.

My first thought was Whisky. Tango. Foxtrot. and my second, Ouch.

Googling suggested that I should look for BIOS updates, but that a number of people have been bitten by this sort of motherboard issue and not been able to get it fixed. I looked at the latest version on intel.com; the release notes were not very clear, but did provide a hint that something in this department had been fixed, so I was optimistic and went ahead with the upgrade. They're slightly scary if you're not running off a UPS, but nevertheless the power held.

And now it works - Linux can see all six gigs - and I am giving them an exercise. I could have done without that!