Vista 32-Bit 2GB vs. 3GB

[MacMan]

Duh......

I see what you mean.

Just as an FYI, I'm not trying to flame M$ for not being able to use all 4GB (or close to) at the same time in their OS. I'm just using them as an example to say that even though 32-bit is capable (at least in theory) of handling 4GB, it's the software that isn't there yet.

In practice, it may not even be possible to make it handle the whole 4GB at the same time, but I bet it can come pretty close. At least much closer than what Windows XP or Vista can today.

Don't worry about the Linux thing, I know you're probably very busy. That is unless you really wanna do it.

Thanks again Rob.

Duh! That's strange. You would think that a super-gigantic corporation like Microsoft could build an OS that was completely 64-bit, but yet, at-the-same-time, capable of running any and all 32-bit programs natively, at full-speed, with out any kind of performance hit? Why two separate OS's, 32 and 64-bit? Why not just the one that handled both in one shot, with full-performance?

Seems rather simple to me. Seriously, how hard can it be? Is it technically impossible as I was told by some Window's technies once? Personally, I know that is not the case. The reason I say that is simply because I have already seen an OS demoed doing just that, one system running both 32-bit and 64-bit simultaneously, and both running at maximum speed, etc.


http://www.apple.com/macosx/leopard/64bit.html

I rest my case.

 

[Rob Williams]

My question is, if I installed another 2GB of CORSAIR XMS2 2GB DDR2 800 and followed the instructions by Microsoft (enable PAE mode so the OS recognizes the 4GB of physical RAM), would there be any overall performance decrease? ie. would my latency or bandwidth decrease compared to what I already have now?

Hi Deth,

I have never had luck with /PAE in the past, but I will give it a go in Vista tomorrow (Friday) and let you know the results of my quick testing. Technically, the results should be near identical to the result here:

4 x 1GB (Note at -no- time would all 4GB be accessed)
5653MB/s - 5652MB/s (59.4ns Latency)

Because of the wider bandwidth, there will likely be a very small latency hike (0.4% - 0.7%) and also an even more minor MB/s drop. I'll test these out tomorrow quickly in both 32-Bit and 64-Bit Vista and see if that proves true.

 

[Rob Williams]

Duh! That's strange. You would think that a super-gigantic corporation like Microsoft could build an OS that was completely 64-bit, but yet, at-the-same-time, capable of running any and all 32-bit programs natively, at full-speed, with out any kind of performance hit? Why two separate OS's, 32 and 64-bit? Why not just the one that handled both in one shot, with full-performance?

Seems rather simple to me. Seriously, how hard can it be? Is it technically impossible as I was told by some Window's technies once? Personally, I know that is not the case. The reason I say that is simply because I have already seen an OS demoed doing just that, one system running both 32-bit and 64-bit simultaneously, and both running at maximum speed, etc.

http://www.apple.com/macosx/leopard/64bit.html

I rest my case.

Windows has a poor base, that's why it won't run all 32-Bit applications perfectly under a 64-Bit environment. I haven't done in-depth testing, so I can't elaborate. My experiences under any x64 OS have been less than stellar.

As for Leopard, I still would like to see 32-bit vs 64-bit benchmarks to see how much of a benefit there would be with the latter. Sure it's a 64-Bit environment, but -how- does that benefit anyone? I've run countless benchmarks and have more often seen decreases under 64-Bit than 32-Bit.

I might test it out tomorrow with 3DS Max w/ 4GB of ram and under 32-Bit and 64-Bit Windows and report the findings here at the same time as the other testing mentioned above. You've got me curious

 

[Deth]

Rob Williams: Do you recommend I go 4 x 1GB or 2 x 1GB + 2 x 512MB? I really want to stick with Windows Vista 32-bit because of the driver problems with 64-bit. I'm not sure if /PAE would solve my problem because so far it seems no one has had any success with it to my knowledge.

I have no performance issues currently whatsoever so I'm wondering if I should even get another gig or two of RAM?

If /PAE works for me, I would much rather get another 2 x 1GB.
If I would ever choose to upgrade to 64-bit Vista later (unlikely), 2 x 1GB would also be the better choice.

If Vista 32-bit won't recognize my 4GB of physical RAM, then going with 2 x 1GB + 2 x 512MB set up would be better economically and save me $100 that would otherwise be wasted.

But how much of a difference can 1GB make if I'm experience no problems and everything is on the highest quality settings and there are no performance issues, everything is smooth.

I think the only reason I want to upgrade is because I'm crazy about more "performance" when in essence I may not notice any. Lol. What should I do?

 

[Cjmovie]

There is no architectural limitation that forces use of 3GB, or even 4GB, of RAM in a 32-bit operating system. Sure, a 32-bit mode of a 64/32 bit processor can only access 4GB at a time. Of this, windows usually uses the top 1GB of space, regardless of how much "actual" RAM it uses. It's called virtual memory. It can map any address within that 4GB to any point in physical RAM, and it has a different mapping for every application (but not thread; this is how it keeps processes safe from each other, and is very common. There are very few OS's not using it, and these most likely use a segmented architecture, like AmigaOS).
Now, there was an addition quite a while ago (Pentium Pro architecture?) that extended the _external_ bus of the processor, called PAE, or physical address extension. This allows RAM of amounts past 4GB (such as 16GB. It varies on implementation) to be accessed by "mapping" it to a range within 4GB, and changing it out for each program. Each individual application is still limited to 3GB (4GB = 3GB for application + 1GB for Windows mapping).

Read up on it:
http://en.wikipedia.org/wiki/Physical_Address_Extension
http://en.wikipedia.org/wiki/Page_table

Or, if you're really daring, do what I did: Order and read the Intel Architecture Developer's manuals. They're free, shipping and everything.

 

[Deth]

Thanks. Think I read enough today. I'm thinking about getting:

CORSAIR XMS2 1GB (2 x 512MB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory


to add to my:

CORSAIR XMS2 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) Dual Channel Kit Desktop Memory Model TWIN2X2048-6400C4


If that sounds like a good idea (or not), let me know!

Thank you.

 

[Rob Williams]

I would not recommend adding more ram to your PC... there's just no need. You are not experiencing any performance issues now... so why bother? I'd overclock it before purchasing anymore ram... better performance > more ram that you won't use.

I tried out PAE in 32-Vista... still shows 2.75GB with 4.00GB installed. Not worth the time and effort to get it working. I'd just stay with what you have, personally.