3gb vs. 4gb of RAM on 32bit OS

[maniac5999]

I have a laptop (Wind U230) that I want to upgrade the RAM on. It currently has 1 2gb stick and an empty slot. I'm stuck with a 32bit OS since there aren't any 64 bit drivers for the laptop.

Now, obviously, a 32bit OS can't address 4gb of RAM, I know the max is 3-3.5gb, but I also know that increasing memory bandwith by going to dual channel mode will help performance. (and with a 1.6ghz K8 I need all the performance I can get) Because of this I've got two questions:

*HOW much of a benefit is dual channel mode?

*CAN I run dual channel with a 2gb stick and a 1gb stick? (is there a performace hit for doing so if I can?)

Just FYI, the reason this is a big deal to me right now is because I can get 1gb for $10 from Microcenter after MIR, but the cheapest 2gb stick is on Newegg for $40.

 

[razel]

Go ahead and try the 1GB for $10. It's a no-brainer upgrade. It should run fine 1GB and 2GB. If it doesn't send it back. If you really want all the performance you can get, especially for a 2.5" (notebook, netbook) HDDs, an SSD is really the next best thing to do.

You can compare basic speed and do a full RAM check using Memtest+

 

[FishAk]

Why do think 32 bit only supports 3 or 4GB? Linux 32 bit supports more than 4Gb with a PAE aware kernel, and Windows is artificially limited. It's your chipset that's the limiting factor.

I'm assuming you're running Windows, and if you install 4GB- providing your board supports it- your OS will use half a GB or so, and leave you with the other 3.5- which will make it look like you're only accessing 3.5GB.

 

[maniac5999]

so is 4gb the way to go? the IGP is going to be using some of this as well. (Yes it's windows) Does anybody know about the Dual Channel memory issue? (I don't know much about it, but I assume it works something like RAID 0, which would make it work poorly or not at all with different size modules) Also, while the 1gb is $10, that's with a $20 MIR, which is a big pain.

 

[Voo]

Why do think 32 bit only supports 3 or 4GB? Linux 32 bit supports more than 4Gb with a PAE aware kernel, and Windows is artificially limited. It's your chipset that's the limiting factor.

I'm assuming you're running Windows, and if you install 4GB- providing your board supports it- your OS will use half a GB or so, and leave you with the other 3.5- which will make it look like you're only accessing 3.5GB.

Actually Windows implemented PAE, but the physical address space is still limited to 4gb because lots of drivers broke - though afaik there are some unofficial kernel patches for Vista out there that disable that limitation (and some server versions don't have that limitation per se)

And not the OS will use half a gb - the MB has to map physical devices (gpu and so on) into some memory range, so that has nothing to do with the OS. Though depending on the mb you can tell it where to map it.

 

[maniac5999]

OK, so which should I get? I'd like to go to Microcenter today and buy it either way. I've had a bad day at work, and could use some instant gratification (even if the 2gb is $4 more there than on the egg)

 

[tweakboy]

Well, 32bit OS only recognizes 3.2GB .. Soo if you put in 4GB it can only access 3.2GB.
If you put 3 sticks for 3GB that would be the way to go, since 200mb of RAM is really not noticable.

This is why we have 64bit and unlimited ammount of RAM. gg and gb

 

[FishAk]

I would put in another 2Gb stick if it was me. You're applications won't be able to access it directly, but since your OS does, and will use it- that leaves more of the "available" memory... well... available.

It's certainly not going to hurt, and for the price, it seems like a no brainer to me.

Voo, you're right, but it looks like we're confusing the OP with all the details. Bottom line is that W7x32 bit will use 4Gb- even though it doesn't show the full 4Gb it in the System Properties page.

 

[maniac5999]

Well, 32bit OS only recognizes 3.2GB .. Soo if you put in 4GB it can only access 3.2GB.
If you put 3 sticks for 3GB that would be the way to go, since 200mb of RAM is really not noticable.

This is why we have 64bit and unlimited ammount of RAM. gg and gb

Well, for the aforementioned reason (no Drivers) 64bit is not an option. :thumbsdown: Do you have any experience how/if Dual Channel mode works with uneven size sticks of RAM? or even how significant the benefit of a dual channel setup is, period?

Also, please inform me where to put that third stick of RAM in my laptop? do I just open up the back cover,drop it in on top of the HSF and let it rattle around?

 

[mv2devnull]

*HOW much of a benefit is dual channel mode?

*CAN I run dual channel with a 2gb stick and a 1gb stick? (is there a performace hit for doing so if I can?)

1. Don't know.

2. Dual channel essentially stripes/interleaves data over two memory modules. That is easy to implement with modules of equal size. With mismatching size the controller should interleave half of the larger module and access the other half like single channel.

I'd do as FishAk said and put a second 2 Gb in.


PS. Some triple channel boards can host 4 or 5 modules in addition to the 3 and 6 configurations. There the MCH (in CPU) can apparently "mix modes", but even that is not "within module".

 

[Chiropteran]

Well, for the aforementioned reason (no Drivers) 64bit is not an option. :thumbsdown:

Are you sure about that? While your computer manufacturer might not supply 64bit drivers, Win 7 has many drivers built in and others availible on windows update. You can download the graphic driver from AMD directly now.

 

[maniac5999]

Hmmmmm, is the 3.2gb max the exact number? because in that case I might just go for the 1gb stick, apparently dual channel doesn't matter THAT much, max difference appears to be 10% in a memory test, and most of the times it's much less. 1.6-4.2% worse performace in games: http://www.tomshardware.com/reviews/PARALLEL-PROCESSING,1705-11.html

EDIT:

Are you sure about that? While your computer manufacturer might not supply 64bit drivers, Win 7 has many drivers built in and others availible on windows update. You can download the graphic driver from AMD directly now.

It's not the graphis driver, i think it's the annoying stuff like wireless driver, etc. i might have to do a little more reasearch on this.

 

[Emulex]

windows 32bit non server products can not access all of the ram. intentionally.

 

[FishAk]

Emulex, I know you're an expert in servers, so obviously, you know that Windows 32-bit server products support huge amounts of RAM. But for some unknown reason, usually blamed on drivers, Microsoft has decided to artificially limit non server Windows memory support


That said, for all practical purposes, unless someone has the expertise to hack Windows license, their 32-bit OS will be limited to something less than 4Gb. However, there's a certain amount of overhead for any given system, and for most people that amount will be in the neighborhood of 500Mb.


So, is my premise wrong, that if you physically have 4Gb RAM, and Windows shows 3.5 or 3.2, that doesn't mean your system isn't using a good portion of the “missing” RAM for overhead? If this is true, someone with 4Gb will have about 3.5Gb available for their applications, while someone with the same setup, but with 3Gb will have only about 2.5Gb left over for their Apps- regardless of what Windows shows in the System Properties page. Since they are artificially limiting memory, Windows can show whatever it wants in the properties box. I don't have access to a 32-bit machine with 4Gb to check with, and am only going off my memory.

Hmmmmm, is the 3.2gb max the exact number? because in that case I might just go for the 1gb stick,

I don't understand. I don't know what RAM your looking at, but on average, it looks to me like a 2Gb stick is a little better than 50 percent more expensive than 1 stick. That would be significant if we were talking about a house or a car, but were talking about saving only 15 bucks here. That's not even one drink for your girlfriend, if you include a tip. And for what? You destroy at least part of your dual channel, and force your programs to 2.5Gb instead of 3.5.

 

[Voo]

So, is my premise wrong, that if you physically have 4Gb RAM, and Windows shows 3.5 or 3.2, that doesn't mean your system isn't using a good portion of the “missing” RAM for overhead? If this is true, someone with 4Gb will have about 3.5Gb available for their applications, while someone with the same setup, but with 3Gb will have only about 2.5Gb left over for their Apps- regardless of what Windows shows in the System Properties page.

Yep that's wrong. The "overhead" you're talking about, comes from the fact that the BIOS has to map some address space to the HW (mainly the GPU for our purposes..).
This means 4gb (32bit address space) - reserved space (depends on the installed hw) = max. available address space.

 

[FishAk]

OK, but that's a limitation of the chip set, and not the OS, correct? So if your motherboard only supports 2Gb, or 512Mb- then that's all you get.

 

[maniac5999]

OK, but that's a limitation of the chip set, and not the OS, correct? So if your motherboard only supports 2Gb, or 512Mb- then that's all you get.

No, it's a limitation of the OS. Regular windows has 4gb worth of 'addresses' everything has to have an address, from the BIOS, to the HDD controller, to the VRAM on your video card. The way windows works is that when it wants to find something it says "Look for X at Address XXXX". XXXX can be the HDD memory controler, which will reinterperate the command in order to search the HDD, it can be BIOS, or it can be RAM.
Now in base 2 notation 4gb is a rollover point--Think of it as a car odometer with 5 digits, you can go 99,999miles before it rolls over. If you try to drive 100,500miles and then ask it "What happened in mile 300" you'll either get an error, or see what you did in mile 100,300 because the computer doesn't realize that there's a 1 in front, and overwrote mile 300 with mile 100,300.

Now, luckily, unlike my car example, RAM is erasable, and windows gets around those fatal errors by saying that it only has 100k miles to work with, and if that's full, you have to erase something to put something new in. Because of this it doesn't 'see' the last 0.whatever gig of RAM out of the 4gig total, because it has already assigned the addresses that it would use to access it.

As an interesting aside, since video memory also gets assigned an address, a card with a lot of ram on it cuts down on the amount of usable regular ram that a computer can use.

A 64bit OS basically adds extra digits to the addressing system (think of it as a odometer that can handle 10,000,000miles instead of 100,000) so you don't need to worry about any of this.

Oh, and Microcenter was out of the $10 1gb stick, so I bought the 2gb, and because I only have 1HDD and an IGP the OS can address 3.5gb, so I'm pretty happy, except I'm getting a "hypertransport sync flood error' again, which I eliminated before by messing with powersaving settings. (MSi said to flash the bios, but for some reason it won't flash, but that's a story for a seperate thread)

 

[jvroig]

If I were in your case, I would just buy the 2GB RAM, it's just $30 difference anyway.

Eventually, your driver issues might solve themselves, perhaps in the next 6 mos or a year, who knows, and you can finally migrate to a 64-bit OS. You'd then be in a better position of not having 3gb and then wanting to go to 4gb and having to throw away a perfectly good 1gb stick of RAM.

That's just how I look at it.

Of course, another way to look at it is would you really need 4GB as opposed to 3GB? And as far as dual channel goes, all testing done has concluded with negligible real-world differences, 5 percent or less most of the time (the greatest delta found was in memory benchmarks - not something you actually do in the real world). Whether it can work or not with sticks of differing sizes depends on the motherboard (at least, it is written in motherboard manuals - the requirements to make dual channel work on it), so perhaps there is a similar documentation for your netbook supplied in the CD or downloadable thru MSI's website.

 

[FishAk]

Thanks for the explination, maniac5999. I suppose the Windows Server 32-bit OSs that can handle up to 128Gb are specialized enough to overcome the driver issues. This is a very complex subject, and my eyes start to glaze over when I read about it. I just don't find it interesting enough personally, which means I won't ever fully understand it.

I'm glad you're happy with your new memory. I have a notebook that I put W7x64 on, with only 2Gb, so I need to upgrade it, but I think my MB only supports 4Gb.

 

[jvroig]

Oh, and Microcenter was out of the $10 1gb stick, so I bought the 2gb, and because I only have 1HDD and an IGP the OS can address 3.5gb, so I'm pretty happy, except I'm getting a "hypertransport sync flood error' again, which I eliminated before by messing with powersaving settings. (MSi said to flash the bios, but for some reason it won't flash, but that's a story for a seperate thread)

Hooray for not reading the entire thread, now I look like a douche trying to answer a solved thread :thumbsup:

In my defense, I scanned your last post, saw it was too long and explaining something that was a known fact to me, and decided to skip over it. That should teach me a lesson. :awe:

 

[coolVariable]

Oh, and Microcenter was out of the $10 1gb stick, so I bought the 2gb, and because I only have 1HDD and an IGP the OS can address 3.5gb, so I'm pretty happy, except I'm getting a "hypertransport sync flood error' again, which I eliminated before by messing with powersaving settings. (MSi said to flash the bios, but for some reason it won't flash, but that's a story for a seperate thread)

Bad RAM?

 

[maniac5999]

Bad RAM?

Doubt it. "Hypertransport Sync Flood errors" seem to be a chipset problem. I think it has to do with feeding the processor more data than it can shove into L2. I re-read my resolution from MSi last time I had it, and it said to reinstall the chipset drivers. I'm going to do that again then crank up memtest just to eliminate the RAM as a possible cause.

Edit: not really sure what the error is, some say RAM some say chipset. the most common answer from manufacturers seems to be "Flash the BIOS" but lots of people report that that doesn't help.

 

[Emulex]

http://www.raymond.cc/blog/archives...ista-32-bit-x86-support-more-than-4gb-memory/

google man. there are hacks. i'm not comfortable to do that myself due to microsoft patching and signed files.

but yeah you can make XP,VISTA,7 32bit use more ram.

why not /USERVA=2850 or /3GB in xp? because microsoft said so.

you do not need to hack the license, you need to crack the file that limits the ram.

 

[maniac5999]

More info, this seems to go a little over my head though:

http://cpu-hypertransport.blogspot.com/2007/06/error-reporting-in-hypertransport.html
"
Sync Flood: When All Else Fails

In some cases, one or more links in HyperTransport may get into a state where ordinary packets cannot be sent reliably. For example, a device may detect a series of CRC errors which indicates to it that either the external link is broken or, more likely, it may not be synchronized with its neighbor with respect to CRC stuffing in the CAD stream. If this is the case, it can't send new packets; it also can't convey the fault using fatal/non-fatal interrupts because they travel in the same channels as other packets.
Sync flood reports errors that cannot be signalled by other methods. It is roughly analogous to the PCI SERR# (system error) event and has a serious impact on the entire chain. Sync flood packets put the chain into an inactive state pending a warm reset to restore normal packet protocol. The behavior of the device initiating the sync flood is slightly different from the other devices which propagate it. The basic rules are described below.
Device Initiating The Sync Flood

1. The device initiating sync flood must have the SERR# Enable bit in the configuration header Command register set = 1 before it initiates a sync flood for any reason.
2. If the device intends to initiate sync flood for CRC errors, buffer overflow errors, or protocol errors, it must first check the corresponding "flood enable" bits in the Error Handling and Link Control registers.
3. The device which initiates a sync flood sets the Signaled System Error bit in the configuration header Status register, LinkFail bit in its Link Control Register, and the Chain Fail bit in the Error Handling CSR. Note: if all conditions for a sync flood have been met, Link Fail is always set — even if the SERR# enable bit in the configuration header Command register is clear (preventing the sync flood packets from actually being sent.)

Devices Detecting Sync Flood

1. Devices detecting sync flood at a receiver input cease all normal packet transmission on the affected chain.
2. Each device sets the Chain Fail bit in its Error Handling CSR.
3. Each device drives sync packets onto all transmitter interfaces, including back to the device which initiated the flood. This assures that sync is seen on all links on the chain.

Sync Flooding And HyperTransport Bridges

1. Bridges set the Detected System Error bit in the Secondary Status register if they see a sync flood on the secondary bus.
2. Bridges may forward a secondary bus sync flood upstream to the primary bus if the SERR# Enable bit in its PCI Command register is set. This is similiar to the behavior of PCI-PCI bridges when SERR# is detected on a secondary bus. The bridge may optionally convert the secondary bus sync flood to a fatal or non-fatal interrupt on the primary bus.
3. Bridges always propagate primary bus sync floods downstream onto their secondary bus(ses).

Miscellaneous Notes

Flooding Continues Until Reset

Once a device commences the sync flood operation, it must continue until a reset is detected on the affected bus. This assures that the sync flood propagates throughout the chain."



Other reading seems to suggest that causes of this can be:
*Bad memory causes memory crash
*HT link running faster than CPU=NB link causes de-sync
*too little CPU, NB or RAM voltage causes instability

I guess it could be memory related, but I'm really not sure. Unfortunately, if the issue is too little NB or memory voltage is a problem, as I can't change that on my laptop (and the memory already seems to be running at 620mhz @1.8v (6-6-6) when both sticks are rated for 800mhz 6-6-6 @1.8v)

 

[razel]

If you haven't done already, you should at least test your RAM with Memtest+ to at least rule it out.