Maximum ram?

[ThunderPants73]

HI,
Does Win XP only recognise 3gb of RAM? I've just bought a 2gb strip to add to my 2gb and my pc only recognises 3gb no matter which slots I put them in.

[Raistlin]

Yep. Afraid so.

---------- Post added at 13:13 ---------- Previous post was at 13:11 ----------

At least I thought so, looking at Google it would appear that there's a trick to get things working.....

[Sir John Luke]

Plenty of info here

http://bink.nu/forums/t/6689.aspx

...or use 64bit edition.

[Raistlin]

Ok, looks like XP can support 4Gb (which I have to confess I thought it couldn't), so I'm guessing it's possible that your motherboard won't support more than 3Gb.

Have you checked the manufacturer's page for your motherboard to check it will take the 4Gb?

---------- Post added at 13:17 ---------- Previous post was at 13:15 ----------

Originally Posted by Sir John Luke

Plenty of info here

http://bink.nu/forums/t/6689.aspx

...or use 64bit edition.

Ahhhh..... Pagefiles, of course - that explains it - nice link

it's not a case of xp can or can't support 4gb of ram it's all to do with the system,32bit or 64 bit
32bit upto 3.5 gb ram
64bit upto 128gb ram

[ThunderPants73]

You guys are great, I learn something new every day, thanks. BTW, does Vista have the same limitations? My mate is soon going to be building a new pc and he likes to bang as much ram in as he can.

[Stuart]

Originally Posted by ThunderPants73

You guys are great, I learn something new every day, thanks. BTW, does Vista have the same limitations? My mate is soon going to be building a new pc and he likes to bang as much ram in as he can.

Yes. It's a limitation of the PC Architecture rather than Windows. PCs running in 32 bit mode (as 32 bit windows would require) can only see 3.5 Gig RAM.

[boroboi]

Stuart is right.

As far as any x86 based processor is concerned, the world ends at 4096MB of address space, or "32-bits"

It's not impossible for a 32-bit system to read more... AMD's opteron processors were capable of addressing 16GB or more... other ways include shoddy hardware manipulations at processor level (which would have to be instruction sets) as well as software hacks like AWE API

Someone called Ian Griffiths explains it in lemans terms

To address 4GB of memory you need 32 bits of address bus. (Assuming individual bytes are addressable.) This gives us a problem - the same problem that IBM faced when designing the original PC. You tend to want to have more than just memory in a computer - you need things like graphics cards and hard disks to be accessible to the computer in order for it to be able to use them. So just as the original PC had to carve up the 8086's 1MB addressing range into memory (640K) and 'other' (384K), the same problem exists today if you want to fit memory and devices into a 32-bit address range: not all of the available 4GB of address space can be given over to memory.

For a long time this wasn't a problem, because there was a whole 4GB of address space, so devices typically lurk up in the top 1GB of physical address space, leaving the bottom 3GB for memory. And 3GB should be enough for anyone, right?

So what actually happens if you go out and buy 4GB of memory for your PC? Well, it's just like the DOS days - there's a hole in your memory map for the IO. (Now it's only 25% of the total address space, but it's still a big hole.) So the bottom 3GB of your memory will be available, but there's an issue with that last 1GB.

[djmagnifique]

32bit xp can handle up to 4gb of memory, however that total includes any add in cards (graphics/sound, etc) so if you have a 512mb graphics card you will get about 3.5gb of ram, if you have a 1gb graphics card you get 3gb of ram, etc.