solaar Posted May 11, 2007 Share Posted May 11, 2007 I just added 2 GB Kingston RAM to my hack (specs below) for a total of 4 GB but I can only see 3.25 in the activity monitor. Same in the 'About' pop-up. The system profiler shows the 4 DIMMs with 1 GB each though. Mandriva too won't show the whole 4GB. I'll have to check again but I reckon I saw 3.45 GB... What am I missing? cheers Link to comment Share on other sites More sharing options...
errandwolfe Posted May 11, 2007 Share Posted May 11, 2007 Well I think one obvious question would be how much RAM do you have dedicated to your on board GMA950? As for how much is too much? Well for my system at least I found the sweet spot was 3 Gb. Enough to run all my Apple apps and still have enough left over to run XP in Parallels full time. Link to comment Share on other sites More sharing options...
solaar Posted May 11, 2007 Author Share Posted May 11, 2007 System profiler says 64MB for the GMA950. When I had only 2GB installed the activity monitor showed just a little less than 2GB regardless, so that can hardly be the issue. It now seems like there's 750MB missing... BTW I found some stuff on several other Mac sites. Here's just one quote but others point to the same direction. The 945 chipset limits to 4 GB physically. But software can only address about 3.2 GB. The 3 GB limit is advertised by Apple to prevent people from wasting money. You can of course put 4GB in there if you buy a second 2 GB DIMM from another vendor. Santa Rosa will not have this "addressing waste" and allow you to use the entire 4 GB. So, did I waste money? If so it would be good to prevent others from doing the same. I've also noticed only very marginal improvements in performance. In After Effects for instance, a particle explosion of a still (720x576 / 4 seconds total length) which took about 32 minutes with 2 GB now takes 30 minutes with 4 GB. I was really expecting something a bit more perceivable with more RAM. Link to comment Share on other sites More sharing options...
errandwolfe Posted May 11, 2007 Share Posted May 11, 2007 Well that is a good thing to know, thanks for the info Solaar. Hopefully this will stop folks from wasting money on more RAM then they need. Link to comment Share on other sites More sharing options...
rhalls Posted May 11, 2007 Share Posted May 11, 2007 I dont think its a software problem, but a problem of th 945 Chipset. On my Asrock conroe 945 dvi, asrock reminds peaople of that limitation. Nothing to do with OSX, just the 945. If OSX could only adress 3.2 GB, why is it possible to put 16 GB into a mac Pro ??? Link to comment Share on other sites More sharing options...
solaar Posted May 11, 2007 Author Share Posted May 11, 2007 I dont think its a software problem, but a problem of th 945 Chipset. On my Asrock conroe 945 dvi, asrock reminds peaople of that limitation. Nothing to do with OSX, just the 945.If OSX could only adress 3.2 GB, why is it possible to put 16 GB into a mac Pro ??? Why can't it address 4 GB then? 4GB is supposedly the physical limit of the 945 chipset. Link to comment Share on other sites More sharing options...
Zulu.Walker Posted May 12, 2007 Share Posted May 12, 2007 Most current motherboards tell you they support 4Gb, but the truth is that many of them will never let you get access to a good chunk of that ram. We thought it would be no big deal to fill the machine up to 4Gb, but after doing so we discovered that only about 3Gb was actually available. It turns out that motherboards typically reserve blocks of space in upper memory for managing PCI devices, and these reserved blocks impose a ceiling on usable ram, even on a 64-bit system. Newer chipsets can remap these reserved blocks out of the usable address range, but the Intel 945 chipset cannot. We naively hoped we could simply switch to a motherboard with the newer Intel 965 chipset, specifically designed to support the Core2Duo. Something I saw while googling, I've also been concerned with upgrading my RAM to 4GB or more on my system. It seems as though it's the 945-chipset limitation and it's not surprising considering that these chipsets are targeted for mainstream users that would usually only install much less than 4GB of RAM. What I'd like to know further is if other "higher" chipsets like the 965 and 975 motherboards have this same problem too. RAM prices are dropping fast, I've been thinking of also going the 4GB route in the near future By the way, the macbooks with the 945-chipset are already having the same problems, they are only able to access up to 3.25GB of RAM. It sucks that you can't access all 4GB, there's only Intel to blame for that Link to comment Share on other sites More sharing options...
solaar Posted May 12, 2007 Author Share Posted May 12, 2007 It turns out that motherboards typically reserve blocks of space in upper memory for managing PCI devices, and these reserved blocks impose a ceiling on usable ram, even on a 64-bit system. Newer chipsets can remap these reserved blocks out of the usable address range, but the Intel 945 chipset cannot. Now we're talking. I found similar articles about this issue but I admit that it sort of leaves me half angry, half insisting. If it's physically there why can't it be addressed? In IT, since when is there a definite cannot ? There are always ways and workarounds, aren't there?.... The part that p*sses me off is obviously the mobo manufacturers not clearly stating 'this board maxes out at 3.25GB - definitely - don't waste your money by putting 4GB in, you'll never get it...' How easy is that to print it somewhere on the box?? Apple is setting a smart example again by limiting the Macbook to 3GB up front. Link to comment Share on other sites More sharing options...
shoarthing Posted May 12, 2007 Share Posted May 12, 2007 . . . What I'd like to know further is if other "higher" chipsets like the 965 and 975 motherboards have this same problem too. RAM prices are dropping fast, I've been thinking of also going the 4GB route in the near future . . . - an i975X [P5WDH] shows all 4GB available in Activity Monitor with memory remapping enabled in the BIOS [3.2-ish GB when disabled] running 10.4.9. System Profiler always shows 4GB. Kernel = recent 10.4.9 'universal' jobbie from irc . . [edit] FWIW I would say that 3GB is ample unless your life = photoshop: you can as stated above run a Linux or Win32 VM happily with this much RAM to hand. Even in Win32 running 2x instances of a greedy MPEG2 encoder [Canopus Procoder2] 3GB is more than enough [2x Procoder 'only' uses around 1.2GB]. . . [edit2] I have no idea whether this indicated remapped 4GB is in fact usable to all OS X applications [assume so], or 100% stable. The DDR2 itself is PC6400 JEDEC-vdimm [1.8v] stuff from Elixir/Nanya & of course fully usable/stable in 64-bit Linux. Link to comment Share on other sites More sharing options...
Zulu.Walker Posted May 12, 2007 Share Posted May 12, 2007 Thanks shoarthing for the shot, anybody else with a 965-chipset with everything running smoothly? I don't think I've ever seen that BIOS option on my mobo, but my manual and everything points out to a maximum of 8GB memory support for all 4 DIMMS. My guess is it'll max out somewhere near 7GB The part that p*sses me off is obviously the mobo manufacturers not clearly stating 'this board maxes out at 3.25GB - definitely - don't waste your money by putting 4GB in, you'll never get it...' How easy is that to print it somewhere on the box?? Well on paper it does, but you know how those engineers and marketing people think. I'm sure they tried 4GB on the 945 chipset, but probably with just the bare essentials. I wouldn't know if there is a workaround regarding this issue as it is a hardware/design issue with the chipset, not the OS. Link to comment Share on other sites More sharing options...
solaar Posted May 12, 2007 Author Share Posted May 12, 2007 Cheers mates. Good info! Link to comment Share on other sites More sharing options...
iji oh Posted May 13, 2007 Share Posted May 13, 2007 Hey, guys: I recently encountered a very similar weird RAM issue. A month ago, I purchased 2 one-gig chips to put into my MSI-7046 mobo (Intel 915P chipset). At the time, I was running JAS 10.4.7/8.4.1 kernel. The system picked up the new memory immediately to show a total of 3.5 gigs. Last night, I used the Egwan method to graduate to 10.4.8/8.8.1 kernel. All went well with the upgrade, and in general the system seems a lot snappier. The problem is that "About this Mac" is showing only 2.75 gigs instead of 3.5. Oddly, "System Profiler" is showing the correct memory configuration. So, I chalked this up to a kernel bug or some such. Then... I checked my bios. It's showing the same 2.75 gigs! WTF? What happened? (FYI: I'm on a Medion m3 Composer 5200, Pentium 4 3.2 GHz, ATI Radeon X1600) What may have been the issue is that in my excitement installing the Egwan patch, I didn't select "custom install", and accidently installed all the patches. There are GMA kexts in there. Could that be the root of the problem?? Thanks for your help (whoever you are...) I appreciate it. (And obviously need it.) Link to comment Share on other sites More sharing options...
Infamous Posted June 23, 2007 Share Posted June 23, 2007 I945 is 32bit chipset which means you can't really use more than cca 3.2GB. Only i965, i975 and newer/server chipsets with 64bit memory controller can utilize 4GB and more. Link to comment Share on other sites More sharing options...
nargot Posted June 24, 2007 Share Posted June 24, 2007 Thanks shoarthing for the shot, anybody else with a 965-chipset with everything running smoothly? I don't think I've ever seen that BIOS option on my mobo, but my manual and everything points out to a maximum of 8GB memory support for all 4 DIMMS. My guess is it'll max out somewhere near 7GB Well on paper it does, but you know how those engineers and marketing people think. I'm sure they tried 4GB on the 945 chipset, but probably with just the bare essentials. I wouldn't know if there is a workaround regarding this issue as it is a hardware/design issue with the chipset, not the OS. i can get a gigabyte ds3 and dq6 to boot and display 4 gb of ram under 10.4.9 however, once the ram usage gets to ~3.4 gb it kernel panics problems with 64 bit i think, anyone know the answer? Link to comment Share on other sites More sharing options...
delish Posted June 24, 2007 Share Posted June 24, 2007 try upgrading your kernel to the latest one, iirc there was noted a 64-bit fix on the latest 8.9.1 kernel. Link to comment Share on other sites More sharing options...
nargot Posted June 28, 2007 Share Posted June 28, 2007 try upgrading your kernel to the latest one, iirc there was noted a 64-bit fix on the latest 8.9.1 kernel. tried all the kernels i could get, none have fixed my problem. any other advice? Link to comment Share on other sites More sharing options...
AppleIIGuy Posted June 28, 2007 Share Posted June 28, 2007 According to this site (Dan's Data) there is a good reason why you only see 3.25 gb. Yes, a plain PC running a 32-bit operating system - and if you're wondering if that includes your PC, then it almost definitely does - shouldn't have more than 3Gb of RAM Large areas of the memory between three and four gigabytes are cordoned off for system devices in exactly the same way that chunks of the Upper Memory Area were purloined in the old days. Once again, the processor (and other system components) can talk with some devices by reading and writing memory addresses up above 3Gb. Link to comment Share on other sites More sharing options...
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