Windows 4Gb limit Question

estebanrey · 23 Sep 2009 at 09:55

Hi all, I'm gonna wait til next year to build a new system, when Windows 7 and DX11 are mainstream and, more importantly, I'll have the cash to do it. Until then I'm looking at one final max out of my P4 system.

Anyway, I'm currently running

Asus P5AD2-E Premium
Intel P4 3.0GHz
2.5GB of mixed DDR2 RAM
ATi X1950 512mb

..now I'm looking at the replacing the built up and mix and match RAM I currently have for 4 Crucial Balistix PC2-8500 1066MHz units and swapping my X1950 (fan has got really noisy) with an HD49XX 1GB card.

Now, as I understand it Windows XP 32 can only recognise and use 4GB total memory and with the above upgrades I will have 5GB (4 in RAM and 1 in VRAM). So my question is should I just buy 3 sticks of the Crucial RAM as the 4th would be wasted?

The confusion for me comes when I get told that RAM works best in matched pairs. Therefore if I only buy/install 3GB one of those wouldn't be in a "matched pair" and thus would I lose performance.

Thanks in advance for any advice!!

95thrifles · 23 Sep 2009 at 10:01

Yeah Id say youre best going for a new set of 2x2 gig, and the 4890, whilst your 32bit Os may not be able to fully utilise all 4 gig of RAM, at least it will be running in dual channel mode (which is the matched pair thing) so should be quick

estebanrey · 23 Sep 2009 at 10:07

Thanks 95thrifles although I will have to get 4 x 1gb as my Mobo can't handle 2gb sticks

** oh and with the 58XX coming out today I might wait a couple of weeks for the 48XX as prices should fall right?

SMAndy · 23 Sep 2009 at 11:49

As a tip, if you're planning on overclocking, you may find that your memory won't clock as high if you're filling all 4 RAM slots. I don't know why, but it doesn't like 1T mode as much if you've got more than 2 sticks.

estebanrey · 23 Sep 2009 at 12:03

SMAndy said:
As a tip, if you're planning on overclocking, you may find that your memory won't clock as high if you're filling all 4 RAM slots. I don't know why, but it doesn't like 1T mode as much if you've got more than 2 sticks.

Ahh thanks, I have always overclocked my system but mainly only to make it capable of running the games I play. All I need it to be capable of for the time being is running BF2 and Pro Evo 2010 which by today's standards are nothing so hopefully I won't need to OC at all with my new bits.

So the concensus is I pay the extra 1gb stick (despite the fact it won't be used) due to the benefits of dual channel?

95thrifles · 23 Sep 2009 at 12:19

yeah, go for the new set, so you know its all matched too
re the OCing, using all 4 DIMMs at once puts extra strain on the NB so youll find as you push your system youll have to up NB voltage more too
The 1T/2T command is relevant regardless of 2/4 DIMMs in use, 1T is a more aggressive command which hinders OCing where as 2T is a bit more loose so allows higher OCing (this is massively simplified as you can imagine)

HazardO · 23 Sep 2009 at 16:23

You definitely want to run your memory as dual channel, this may be possible with 2x 1G and 2x512M (1.5G in each channel), but you might not be making much of a saving, and 512M sticks aren't that easy to get hold of anymore.

estebanrey · 23 Sep 2009 at 21:44

HazardO said:
You definitely want to run your memory as dual channel, this may be possible with 2x 1G and 2x512M (1.5G in each channel), but you might not be making much of a saving, and 512M sticks aren't that easy to get hold of anymore.

Talk of hard to get hold of, OcUK doesn't sell any 1Gb sticks of 8500/1066Mhz.

Another question then, is it even worth me going for the highest or should I just go with the PC2-6400/800Mhz? My mobo does support a 1066 FSB but is getting that high only with overclocking?

To be fair seeing as I can get 1Gb sticks that are 8500s for 15 quid there's not much of a saving.

Final noob question, does buying 'matched pairs' mean buying a 'kit' as I was just going to buy 4 stick seperately. I thought just getting ones that are the same spec was all that was advised but I've heard some since say they should be from the same production run (i.e bought in a kit)?

Thanks again guys

dzlben · 24 Sep 2009 at 15:06

delete

HazardO · 24 Sep 2009 at 15:21

Ideally you should buy them in pair kits. (Unless you can find a kit with 4 sticks)

Corasik · 24 Sep 2009 at 16:29

What do you use the computer for, Windows 32bit has another limitation. For the majority of programs (which are not programmed to accept PAE memory), any single program running under windows can only access 2GB of personal memory space. For a computer running games and a few minimal background tasks such as antivirus etc, going past 2.5G on 32bit windows will give very minimal benifits at all.

Slap in a new graphics card, and wait for windows 7/64bit.

To be honest though, depending on what you play, the Pentium 4 is the biggest bottleneck. Even a mear 1.8Ghz Core 2 E6xxx series can beat a pentium 4 at 3Ghz.

In my opinion its not the best idea to change the ram on the system at all.

The graphics card is fair game though, as assuming your P4 has PCI Express x16 slots you should get some benifit.. It will likely be cpu bottlenecked though, the P4 are not good gaming chips.

Fire Wizard · 27 Sep 2009 at 12:06

estebanrey said:
Now, as I understand it Windows XP 32 can only recognise and use 4GB total memory and with the above upgrades I will have 5GB (4 in RAM and 1 in VRAM). So my question is should I just buy 3 sticks of the Crucial RAM as the 4th would be wasted?

This isn't really the correct way to think about things. You don't have 5GB of RAM. You simply have 4GB of physical memory and 1GB VRam. Though, as you're using Windows x86, the system will only be able to address a large portion of that physical memory and not the full 4GB as Mark Russinovich explains below:

Mark Russinovich said:
32-bit Client Effective Memory Limits

While 4GB is the licensed limit for 32-bit client SKUs, the effective limit is actually lower and dependent on the system's chipset and connected devices. The reason is that the physical address map includes not only RAM, but device memory as well, and x86 and x64 systems map all device memory below the 4GB address boundary to remain compatible with 32-bit operating systems that don't know how to handle addresses larger than 4GB. If a system has 4GB RAM and devices, like video, audio and network adapters, that implement windows into their device memory that sum to 500MB, 500MB of the 4GB of RAM will reside above the 4GB address boundary, as seen below:

Pushing the Limits of Windows: Physical Memory

Regarding weather to install 3GB or 4GB due to the above. If you only install 3GB of RAM, you could well be missing out on the odd 200mb because you may find that your system can actually address around 3.2GB of physical memory. If you only have 3GB of RAM installed in the system, the system will only obviously be able to use as much memory as you have physical installed, providing the system is able to address 3GB or more in the first place. Even if the system will only be able to address 2.8GB of physical memory, weather you have 3GB or 4GB of RAM installed, the system will be addressing the exact same amount. So, there is absolutely no reason why you shouldn't install 4GB of RAM.

When you migrate over to Windows x64, which is able to address much larger quantities of memory, if you already have 4GB as opposed to only 3GB of RAM, you will obviously have an extra 1GB available to you without needing to buy additional RAM. Unless of course, you need more than 4GB of RAM anyway.