Tesla Posted December 17, 2004 Share Posted December 17, 2004 hi all, new here... I just purchased the asus p5ad2 premium (has latest bios, 1009) with an intel 3.4 ghz and 4 GB of corsair 'value select' ram (DDR2, 4 x 1GB sticks which have samsung K4T51083QB-GCD5 modules; these sticks came in matched pairs). Each of the 4 sticks checks out perfectly in memtest86 under default bios settings (no oc'ing, everything on auto). In fact, any combination of 3 of the 4 sticks works perfectly, but when I put all 4 sticks in, only 3.2 GB is reported in BIOS and memtest (instead of 4 GB). Furthermore, when I use the memory size 'probe' feature of memtest, it hangs (but only when all 4 sticks are in). One of my apps needs about 3 gigs of RAM, so I really need all 4 recognized. Also, I've noticed that memtest seems to take substantially longer than it should for a single pass (default settings) with all 4 sticks in the mobo; still trying to quantify this, though. I saw earlier that there were some PSU issues, but I know I have a solid PSU (660 W continuous, 720 W peak, entry-level server PSU from enermax) that is road-tested. Oh, and vid card is an x800XT from sapphire. Haven't even installed any HD's yet! Does anyone have any experience with this? I haven't had much luck with ASUS yet (still waiting), so anything would be greatly appreciated. All I've gotten is handwaiving about x86 architecture limitaitons and generic statements that 'some' types of RAM work with a full 4GB loadout. Many thanks for any advice, A Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted December 17, 2004 Corsair Employees Share Posted December 17, 2004 First off this is a chipset limitation. Most X86 systems will see 4 Giga-Bit of memory, but the translation from bits to bytes would make it about 3.6 Gigabyte and then you have to subtract memory for your Video and CPU Cache and any other devices that have cache and that will be the total amount of memory the system will see. In addition the bios will reserve some memory for PCI devices as well. In addition, if you are using WinXP then you will not have more than 2.0 Gig of memory available for Applications. That too is a limitation with in Windows 2k and XP. Please do a bit more research and I think you will find answers? Link to comment Share on other sites More sharing options...
Tesla Posted December 17, 2004 Author Share Posted December 17, 2004 First off this is a chipset limitation. Most X86 systems will see 4 Giga-Bit of memory, but the translation from bits to bytes would make it about 3.6 Gigabyte and then you have to subtract memory for your Video and CPU Cache and any other devices that have cache and that will be the total amount of memory the system will see. In addition the bios will reserve some memory for PCI devices as well. In addition, if you are using WinXP then you will not have more than 2.0 Gig of memory available for Applications. That too is a limitation with in Windows 2k and XP. Please do a bit more research and I think you will find answers? Unfortunately, I don't think it's a conversion problem. When I use all four sticks, only about 100 MB more RAM is recognized than when I use 3 sticks. Thus, instead of showing an extra ~1 GB more RAM (minus the overhead for conversion), I'm only seeing about 100MB more when I insert the 4th stick. Something just doesn't seem right with this. And thanks for the reminder about windows; I'll be using a modified linux OS for the heavy stuff. Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted December 17, 2004 Corsair Employees Share Posted December 17, 2004 How much memory does Linux see? Or what is shown as the total in Memtest? Link to comment Share on other sites More sharing options...
Tesla Posted December 17, 2004 Author Share Posted December 17, 2004 How much memory does Linux see? Or what is shown as the total in Memtest? memtest & BIOS both show 3199 MB with 4, 1GB sticks installed; memtest reports dual channel interleaved in this configuration, and the transfer speed is posted as about 3000-3200 MB/sec (do you think that's low for 4 4 4 12 in dual chann @ 533MHz?). Still waiting for a spare HD to get linux up, but this fact that memtest crashes when 'probing' total memory size is bothering me. at this point, I'm thinking it's a fundamental mobo limitation; I guess my key question is if changing RAM to a different line could fix this sort of thing, or is a new mobo is in order... many thanks. Link to comment Share on other sites More sharing options...
Corsair Employees RAM GUY Posted December 17, 2004 Corsair Employees Share Posted December 17, 2004 Well that is not uncommon to see that type of issue when using that feature in memtest, because it will allow you to access memory that is used by the system and will sometimes make the system unstable. Not to mention this MB and or platform is still new. But only having 3.2 Gig is a bios and or chipset limitation. Also what bios version do you have installed? The latest version is Bios 1.009! And have you tried these modules 2 at a time and do they show the total size when you have only 2.0 Gig of Ram? Link to comment Share on other sites More sharing options...
Tesla Posted December 18, 2004 Author Share Posted December 18, 2004 Well that is not uncommon to see that type of issue when using that feature in memtest, because it will allow you to access memory that is used by the system and will sometimes make the system unstable. Not to mention this MB and or platform is still new. But only having 3.2 Gig is a bios and or chipset limitation. Also what bios version do you have installed? The latest version is Bios 1.009! And have you tried these modules 2 at a time and do they show the total size when you have only 2.0 Gig of Ram? ah, didn't know about memtest instability in that mode; thanks. Yep, I have latest bios, unfortunately ;| Every combination of 3 or fewer sticks works and reports the correct size; but putting all 4 in causes the reporting problem and the memtest crash. Still waiting on ASUS... I definitely agree that it is a mobo problem. I'd like to use the mobo (really nice feature set), so I'm hoping that the RAM conflict is specific to only certain types of RAM... maybe there's a brand that'll work for a full 4GB loadout. Have you ever heard of some types of RAM working in a full loadout but other brands of the same type not working? It's an unfortunate problem... Link to comment Share on other sites More sharing options...
Tesla Posted December 19, 2004 Author Share Posted December 19, 2004 AHA! I have now installed a WD Raptor 36GB HD with winXP, sp2. Windows still reports only 3199MB RAM. I ran SiSoftware's Sandra Lite 2005, and it reported that 512MB of RAM was allocated as reserved for video caching (analagous to AGP aperature I suppose, but for PCI-E). ******************************************* So if anyone else has this problem, this is where we're at: The good news is Sandra was able to detect all 4 sticks of ram properly and could probe through the entire 4GB RAM bank. The bad news is the ASUS P5AD2 Premium v1009 BIOS is reserving a full 512 MB of my 4GB RAM bank for video cache! What's more, there is no immediate BIOS setting to control the amount of RAM allocated to the video cache. I've contacted ASUS about this and am eagerly awaiting a reply. ******************************************* Does anyone know if there's a way to control the size of the video cache from the o/s (windows or linux)? Is it strictly a BIOS-mediated allocation? Take care. Link to comment Share on other sites More sharing options...
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