How much memory can my computer hold?

November 25, 2007 10:53 AM

How much memory can my computer hold? My computer specs: Dell XPS 600 OS: WinXP Professional 5.1 SP2 (Build #2600) CPU: Intel Pentium D , 2.99 GHz, 1024KB Video: NVIDIA GeForce 7800 GTX (1920x1200x32bpp 60Hz) I went on crucial.com and their scanner said my computer can have up to 8 gigs of memory but a friend of mine told me that XP can actually only hold 3 gigs of ram. How true is this? I currently have 2 gigs of ram and I was looking to go as high as 5 mainly because I work with After Effects a lot and rendering is a pain in the ass. Thanks in advance everyone.
posted by cheero to computers & internet (14 comments total)

XP is a 32-bit OS, which means the memory space is limited to 4G.

However, some of that memory space must be used for memory-mapped I/O, such as on your graphics card.

Basically, your friend is right. Because of the number of memory slots you have (probably two pairs, which must be filled in pairs) and the configurations that memory comes in, 3G is your limit. If you put more in, the OS wouldn't use it.
posted by Steven C. Den Beste at 10:58 AM on November 25, 2007

An OS with 32 bit pointers can only directly address 4 GB of ram (2^32). Your pentium-D might support more address lines, but Windows XP doesn't know what to do with them.

Also, most OSes reserve 1-2 GB of memory for themselves. Sometimes you can tune your OS to give more of that memory back, sometimes not. I wouldn't bet on WinXP allowing access to more than 2GB of RAM.

There is a 64 bit version of Windows XP, but very few drivers work with it. You might need to switch to Vista or a Mac.
posted by b1tr0t at 10:59 AM on November 25, 2007

There does exist a 64-bit version of XP, but you're not using it. And it wouldn't do you any good anyway, or not much. Your app is a 32-bit app, and even if it were running in a 64-bit OS on a computer with 8G of ram, your app would be limited to 2G of RAM. That's how the application memory space is handled with XP.
posted by Steven C. Den Beste at 11:00 AM on November 25, 2007

Thanks for the advice everyone. I currently have 4 slots x 512 so I was looking for an upgrade. That really sucks about XP. Bastards! Looks like I have no other choice than to go only as high as 4 gigs.

Appreciate it everyone. Thanks again.
posted by cheero at 11:05 AM on November 25, 2007

If you put in 4G, you won't be able to access all of it. You're probably better off just getting two new memory sticks and going up to 3G, because that's pretty much all you'd be able to use even if you put in 4G. Don't waste your money.
posted by Steven C. Den Beste at 11:19 AM on November 25, 2007

Instead of paraphrasing, here's the MSDN article.
posted by kcm at 11:43 AM on November 25, 2007

You will not get anything above 3 Gig.
posted by StickyCarpet at 12:19 PM on November 25, 2007

3.25Gb is what I have showing in Vista with 4Gb installed.
posted by kenchie at 12:55 PM on November 25, 2007

I use this.
posted by ydnagaj at 12:57 PM on November 25, 2007

Jeez, I didn't even read the whole post ;) Sorry, ignore this.
posted by ydnagaj at 12:58 PM on November 25, 2007

If you put in 4G, you won't be able to access all of it.

3GB is the limit for user space. If you have 4GB, the kernel will use the other 1GB, so all of the memory will be used, and 4GB would theoretically deliver better performance than 3GB (if memory is the bottleneck for whatever applications you're using).

From the MSDN link given above, it looks like you'll have to play around with some settings to get the system to use all 4GB.
posted by mpls2 at 1:21 PM on November 25, 2007

Here's a fairly detailed article on why a 32-bit OS can only use 4GB of RAM.
posted by entropic at 2:50 PM on November 25, 2007

You can give Vista a try. I kinda like it on the one machine I have it installed on.
posted by Mr. Gunn at 5:21 PM on November 25, 2007

If you put in 4G, you won't be able to access all of it. You're probably better off just getting two new memory sticks and going up to 3G, because that's pretty much all you'd be able to use even if you put in 4G. Don't waste your money.

Wrong. Do not use 2 + 1, this will leave you unable to use dual-channel memory configs. Use 2x2GB sticks, accept the ~750MB loss, and be happy with the ~15% memory throughput speedup that properly using matched RAM sticks provides you with.
posted by Ryvar at 12:14 PM on November 26, 2007