Vista and 4GB RAM

[bistro]

Need some help here guys. I loaded up an extra 2GB RAM on the system (identical to the ones already in there) in anticipation of switching over to 64-bit tonight. I know that 32-bit Vista will recognize only 3.12 of that, but i just wanted to make sure the RAM was OK before doing the install. The BIOS recognized all 4 gigs....however, Vista 32-bit is only recognizing 2.3 gigs. I tested the system with just the old sticks, then the new sticks (in different and same slots). The BIOS recognized them as 2 GB and so did Windows. But when all 4 sticks are in there, again Vista recognized only 2.3. BTW...Sisoft Sandra ALSO only saw 2.3 gigs. I went to msconfig and made sure the advanced settings for "maximum memory" was unchecked. I also tried it with "4096"....no change. I also tried it with the paging file turned off...nada. I even turned off SLI just in case that was stealing some memory...still nothing.

I'm not going to change over to 64-bit until I see some indication that the system is recognizing the RAM. Like I said, I do not expect to see all 4 GB with 32-bit, but I should be seeing more than 2.3GB!

Any ideas?

[SpywareDr]

How much RAM is on your video card(s)?

Total addressable RAM is 4GB ... minus the RAM on your video card(s) (and whatever else).

[Tuttle]

It's not all the RAM on your video card(s) -- they use an aperture to address different parts of video RAM at different times, so worst case hit from a video card is usually 256 MB.

If you're planning to go 64-bit tonight, why not just do it? If there's a RAM problem you can still deal with it afterwards, but since the BIOS sees all 4 GB I suspect it's fine.

I believe Vista SP1 splits the memory into installed/available to reduce the confusion from this sort of thing; since you're facing a reinstall anyway to go to 64-bit you could try installing SP1 RC0 and see if that shows all 4 GB.

[bistro]

Gee...I think I'll do that....and while I'm at it, I think I'll just go and jump off the nearest cliff and use yarn for a bungee cord.

Seriously though, I just expected 32-bit to recognize at least 3 GB of that memory. When I see just 2.3 out of 4, I get a little concerned. I just might go ahead with it anyway...just don't want to run 64-bit with just 2 GB.

Total vid memory on the two cards is just 512mb. Even if that RAM is deducted, it still wouldn't account for all the "missing" RAM...and Sisoft Sandra should be detecting ALL of it despite what Windows recognizes.

[SpywareDr]

The maximum number of memory addresses in a 32-bit Operating System is 4GB, ( 2 ^ 32 = 4,294,967,296 ).

So, when you have 4GB of RAM installed in a 32-bit system, the Operating System cannot use the FULL 32-bits worth of addresses for memory alone because there are other components (such as your video card) that also need address space. And ALL addresses must be mapped within in that same 32-bits worth of space.

For example, if you had two 768Mb graphics cards installed they would eat up 1.5GB of your 32-bit memory addresses all by themselves, cutting you down to a 2.5Gb ceiling ... and that's before taking the other reserved memory addresses into account.

Ask Dan: What's with the 3Gb memory barrier?
http://www.dansdata.com/askdan00015.htm

...

Large areas of the memory between three and four gigabytes are cordoned off for system devices in exactly the same way that chunks of the Upper Memory Area were purloined in the old days. Once again, the processor (and other system components) can talk with some devices by reading and writing memory addresses up above 3Gb.

The difference is the size of the reserved areas.

Windows memory allocations

Windows users can see all of the reserved memory areas on their PC in Device Manager, using the View -> Resources By Connection option. This is what that view looks like for the PC I'm using now.

The addresses are all in hexadecimal, which makes it less than instantly obvious to the untutored viewer which reserved areas are tiny (and usually old) and which large (and all relatively new). Spend the time to figure it out, though, and you can see the old backwards-compatibility stuff and the new 3Gb-barrier stuff, plain as day.

Hex addresses A0000 to BFFFF, for instance, are still assigned to the video card (a GeForce 7800 GT, in this case). That's addresses 655360 to 786431 in decimal, 640 kilobytes to 768k. This is the old 128 kilobyte reservation for the monochrome, CGA and EGA graphics buffers, still there in case you find your old Leisure Suit Larry disk and want to see if it works.

In the above picture, though, you'll see a much more considerable reservation from C0000000 to CFFFFFFF, that's also assigned to my video card. That's 268,435,456 bytes, equal to the 256 megabytes of memory on the card, and it's the chunk of memory addresses that system devices use when they want to access the card's memory.

If I had a video card with 512Mb or 768Mb of memory on it, it'd take up even more space in the 3Gb-to-4Gb memory map.

And if I were still using an AGP graphics card, there'd be another block of memory reserved for the AGP aperture, used when devices on other buses in the computer want to talk to a graphics card on the AGP bus. I've got a PCIe graphics card, though, which sits on the same bus as all of the other stuff and so doesn't need an aperture.

(If you've got a computer with one of those cheap graphics adapters that uses system memory instead of having RAM of its own, it will of course eat some of your RAM no matter how much you've got installed.)

Power users with a hankerin' for dual graphics cards may be experiencing something of a sinking feeling, at this juncture. Yes, the 256Mb reserved for my little old graphics card means exactly what you think it means: Those two 768Mb graphics cards you can totally justify buying will eat one point five gigabytes of your 32-bit memory map all by themselves, cutting you down to a 2.5Gb ceiling before you even take the other reservations into account.

This also explains why 1Gb graphics cards haven't hit the consumer market yet. Nobody yet needs anything like that much memory on one card for any desktop computer purpose, but some people would still be very happy to pay for such a card just for the pose value. It'd eat the whole of the fourth gigabyte of their system memory, though. And then they'd probably demand their money back.

(This fact has apparently not stopped certain unscrupulous companies, coughDellcough, from allowing people to buy a computer with WinXP, 4Gb of RAM, and a pair of Nvidia's oddball 1Gb GeForce 7950 GX2 cards. Result: 56.25% of the installed memory absent without leave. You might as well have only bought 2Gb.)

...

[jenae]

Hi, thats a nice board you have there I just read a long review about it, now 2.3GB with 2 GPU in SLI is what Vista ultimate returns... go with the 64 let us know how you like it SS seems pleased and I am thinking that way myself.

[lgbpop]

I'd say just install the 64-bit version and look for 4GB. Vista is such a resource hog I wouldn't be surprised if it ate 1GB of RAM anyway even before the video loss.

[bistro]

Vista is such a resource hog I wouldn't be surprised if it ate 1GB of RAM anyway even before the video loss.

Yeah....that and the fact that they decided to use only MY computer for the SETI search....that might be the cause of so much memory being burned up.

I think I'll take y'alls advice and just install the 64-bit. More than likely the whole friggin' 4GB will show up. Thanks for all the info...I DID notice that my graphics cards were taking up a lot of memory address allocations.

Jenae: I do like this board. It was a choice between the Asus Striker Extreme and the EVGA. When I saw Maximumpc's Dream machine, they went with the EVGA over the Striker and I trust their judgement. It's powerful and has some great overclocking capabilities.

Thanks, folks

[bistro]

I installed Vista 64-bit and the 4 GB showed up fine....right before the BSOD appeared on the next boot...and the next.....and the next. Finally found out it needed a Microsoft update to correct the (fairly common) problem. MS in it's infinite wisdom did not include the patch with the 39 updates required on a clean installation....go figure. Everything is running fine now, except for my scanner....too old and Canon isn't making any 64-bit drivers for it....32-bit won't install. Time for a new one anyway....

Thanks again for the responses.

[bistro]

And one more thing....

Interestingly enough, when I had just 2GB RAM running at 800mhz, I had a Windows Experience Index memory score of 5.6. Now with 4GB running at 1066 mhz, the score went down to 5.4.

Shows how marvously accurate that Windows Experience Index is....

[liam858]

It's the mobo, filling all four slots can cause instability, sometimes you need to up the MCH voltage to stop problems, i doubt you're bothered what MS think of your hardware anyway, i know i don't.


Liam

[bistro]

It's the mobo, filling all four slots can cause instability, sometimes you need to up the MCH voltage to stop problems, i doubt you're bothered what MS think of your hardware anyway, i know i don't.


Liam

You....you.....you....you don't care what MS thinks about your hardware?!? *sniff!*.....


You're right....I could care less too... I have the RAM set up within the BIOS at Optimal...it's running at the stock 1066 now.