Memory ( RAM ) Question

[ReallyDedPoet]

I am not much of a techie, but the more you dabble in this stuff the more you learn.

Anyway, had a rig built back in the spring, installed 2 gigs of DDR2 800ghz Memory put in, but am now realizing that my Motherboard can only handle up to 667ghz. The rig works fine, no problems ( yes I realize that I am not utilizing the entire capabilities of the RAM that I have ). I want to kick the lad that built the thing and said the RAM was fine in the A@%, but for now want to ask the following.

Will this set-up have any adverse effects on my system in the long run. Also, can I mix other ram in with what I have ? I still have two slots available.

Thanks in advance.


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[d@rk51d3]

They will all drop to the performance of the lowest rated simm that you install. So if you bung in a cheap old stick, the rest will drop to that particular sticks performance limit.

No other adverse effects tha I know of.

[ReallyDedPoet]

They will all drop to the performance of the lowest rated simm that you install. So if you bung in a cheap old stick, the rest will drop to that particular sticks performance limit.

No other adverse effects tha I know of.

OK d@rk51d3, so my current 800mhz RAM is only going to perform at 667mhz. So anything I a get now should be at least 667mhz, that correct.

Thanks :up: for the quick response by the way.


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[d@rk51d3]

Yep, at the minimum. I'm not really up with what current motherboards run, but if its around the 800 mark, I'd keep them matched. At least you could shift them to a new system in the future, and not worry about degraded performance.

[Reece]

It just means that the ram is capable of faster speeds, the ram will simply run cooler, it doesn't matter what ram you put in the other 2 banks as long as it is not slower than 667mhz.:yep:

Edit: Posted same time there D@rk51d3 & RDP, shows how slow I am!

[ReallyDedPoet]

Yep, at the minimum. I'm not really up with what current motherboards run, but if its around the 800 mark, I'd keep them matched. At least you could shift them to a new system in the future, and not worry about degraded performance.
I may try a couple of sticks of 667mhz and see what happens when mixed with the 800s.

@ Reece. Thanks. Sounds like they will run ok.


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[d@rk51d3]

Yep, at the minimum. I'm not really up with what current motherboards run, but if its around the 800 mark, I'd keep them matched. At least you could shift them to a new system in the future, and not worry about degraded performance.
I may try a couple of sticks of 667mhz and see what happens when mixed with the 800s.

@ Reece. Thanks.


RDP

They'll be good for a quick fix now, unless youre using XP, which has a limit of 3GB........ I think:hmm:

You just won't want to use them in a new (upgrade) system in the future though, else it will bring your new baby to a crawling pace as your new ram will be brought down to 667.

Still, they should be cheap enough for a quick blast now.
Have fun.:up:

[ReallyDedPoet]

Yep, at the minimum. I'm not really up with what current motherboards run, but if its around the 800 mark, I'd keep them matched. At least you could shift them to a new system in the future, and not worry about degraded performance.
I may try a couple of sticks of 667mhz and see what happens when mixed with the 800s.

@ Reece. Thanks.


RDP
They'll be good for a quick fix now, unless youre using XP, which has a limit of 3GB........ I think:hmm:

You just won't want to use them in a new (upgrade) system in the future though, else it will bring your new baby to a crawling pace as your new ram will be brought down to 667.

Still, they should be cheap enough for a quick blast now.
Have fun.:up:

Thanks :up: I will check on the 3 gig thing.


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[ReallyDedPoet]

Had a quick look, sounds like the max you can use is 4gigs, recognized as 3.5 in XP.


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[Go4It]

My friend just built a new system an wasn't getting 800 mhz FSB an after a little digging we found it was the CPU, AMD 5200 x2, it seems there are 2 different 5200 out there an just happens the one he got was the worst choice. After returning the CPU, NewEgg, an getting a AMD 6000 x2 all runs fine.....

[ReallyDedPoet]

Just to follow up here, I am still a little unclear, would it be better to just add one more stick of Ram ( 1 gig )versus two as XP can can only read 4 gigs as 3.5.

As indicated above, I presently have 2 gigs.

Thoughts.


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[thefretmaster]

they most usually have to be added in matched pairs. so for 1 gig its 2 x 512mb sticks ddr2 and 2 gig is 2 x 1gb ddr2 (ddr wont work with a ddr2 motherboard (i think))

[ReallyDedPoet]

they most usually have to be added in matched pairs. so for 1 gig its 2 x 512mb sticks ddr2 and 2 gig is 2 x 1gb ddr2 (ddr wont work with a ddr2 motherboard (i think))

I have two gigs of DDR2, would it be worth it to add another two, I am running XP Home Edition, 32 bit.


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[Hitman]

Is a motherboard upgrade entirely out of question? :hmm:

Currently ASUS offers a nice motherboard (The P5K) which has slots for memory DDR2 and DDR3, and would allow you to run your memory at 800 MHz but also to later upgrade to 1066 MHz or even 1333 MHZ DDR3 while keeping the board. It also is good for any current dual core and quad processor :yep: so for less money than buying more RAM you could see an overall system improvemnt by using the full power of your memory and at the same time being ready for future upgrades.

[swdw]

Yep, at the minimum. I'm not really up with what current motherboards run, but if its around the 800 mark, I'd keep them matched. At least you could shift them to a new system in the future, and not worry about degraded performance.
I may try a couple of sticks of 667mhz and see what happens when mixed with the 800s.

@ Reece. Thanks. Sounds like they will run ok.


RDP

On a side note- always put the slowest ram in the first memory slot. What hasn't been brought up is that even though your board will only go to 667, the memory controller will also utilize the CAS latency and timing of the chip in the first memory slot. So- to be safe, always put the slowest chip in the first slot and the system ahould cruise right along.

Also, the guy who built the system may have thrown in the 800MHz cuz he got a good deal on it. At the time I built my system, I found some 800 MHz, Super Talent hi performace matched ram, on sale for cheaper than I could get normal quality 667 memory. Just got lucky that day. So that may be why you have the 800 speed

[swdw]

they most usually have to be added in matched pairs. so for 1 gig its 2 x 512mb sticks ddr2 and 2 gig is 2 x 1gb ddr2 (ddr wont work with a ddr2 motherboard (i think))
No you don't have to do this, you just get better performace if you're going to overclock by using matched sets.

You're right DDR and DDR2 are different animals DDR uses the leading edge of the clock pulse for read/write operations, DDR 2 uses the leading and trailing edge of the clock pulse.

I have two gigs of DDR2, would it be worth it to add another two, I am running XP Home Edition, 32 bit.

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First, windows programs (not windows itself) have a hard time seeing anything over 3 GB, even though the OS actually see's all of it, the reported space is less than 4, reasons are n the article below.

Next, you'll see some improvement but not as much as you think- depending on the program. It will never try to access more than 2 gigs under a 32 bit Windows OS and will only do so in a 64 bit OS if a flag is set in the program by the programmers.

Here's a good explanation from annandtech:
Warning- LONG
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A Primer on Windows' Memory Management In 1986, Intel released the 386 processor, which offered support for a new instruction set (IA32), that was an extension of the original x86 instruction set. Among the most notable features in IA32 was an increase in the amount of memory the CPU could address, moving from 20bit addressing(1MB) to 32bit addressing(4GB)(ed: this is not including the convoluted mess that was segmented addressing). All x86 CPUs released since then have supported the same instruction set, including the same 4GB limit. Only recently have 64bit x86 CPUs been released, and while they support more than 4GB of memory, still are limited to 4GB when operating in 32bit mode.

As we have mentioned in previous articles, most modern system running in 32bit x86 mode have trouble seeing and using more than roughly 3GB of memory. This is because part of the total 4GB of memory space (not the physical memory) is reserved for various functions, such as computer components transferring data (http://www.anandtech.com/gadgets/showdoc.aspx?i=3034&p=2#) between each other using memory-mapped input-output(MMIO). The textbook example of this is the CPU transferring data to the memory of a video card, where a chunk of the address space equal to the size of the memory of the video card is reserved by the video card, and any data sent to those addresses actually ends up going to the video card. This design has many technical merits, but it makes the consumed memory addresses unavailable for use with physical memory.

Things only get more complex as we start including the operating system (in this case Windows) in to the equation. The above is actually handled by a combination of Windows and the BIOS, meanwhile Windows also needs some address space so that programs (http://www.anandtech.com/gadgets/showdoc.aspx?i=3034&p=2#) can communicate with the Windows kernel, for storing buffers, for storing memory tables, etc; all of which means we have lost even more address space. All of the above besides preventing us from addressing 4GB of physical memory are also the cause of the actual 2GB barrier that is the problem.

Quickly, there is one more pre-requisite piece of information: virtual address space. For a 32bit Windows application (http://www.anandtech.com/gadgets/showdoc.aspx?i=3034&p=2#)(Win32), each application has a full 4GB worth of private addressing space that it can use, which again is 32bits and a result of how a 32bit processor works. How the above exactly works is beyond the scope of this article, but it's sufficient to say that at some point virtual addresses get translated in to other addresses for mapping data between the application and physical memory or the swap file. The important thing to take from this is that each application has its own 4GB virtual address space, regardless of the hardware the computer contains or what applications are running. Now we may begin to understand the 2GB barrier.

Due to design reasons outside the scope of this article, Windows takes a pre-determined portion of each application's virtual address space and reserves it for itself. Windows uses its portion of the virtual address range for all of the address needs listed above. At the end of the day, and what really matters, is that in designing Windows Microsoft opted to split up the virtual address space of an application in half; 2GB goes to Windows (kernel space) and 2GB goes to the application (user space). Under normal circumstances this 2GB of space is all a 32bit application has to work with, this is the 2GB barrier and as we'll see is the cause of the problems with Supreme Commander.

It is also worth noting at this point that virtual address space is not directly correlated to physical memory size. Windows and any applications running under it may use up to all of their allocated virtual address space, with Windows simply swapping data between the hard drive and physical memory if the amount of physical memory needed is in excess of what's available - this is virtual memory, not to be confused with virtual address space. The only meaningful relation between virtual address space and physical memory is that the amount of physical memory an application can use can never be greater than its virtual address space. The user space must take up a larger portion of the virtual address space if an application is to use more than 2GB of physical memory.

[swdw]

A Primer on Windows memory part 2- From Anandtech.com

Removing the 2GB Barrier As it turns out, it's possible and actually quite easy to move the 2GB barrier by increasing the size of the user space, but at the cost of reducing the size of the kernel space. Under Windows XP, this is the fabled "/3gb" switch for boot.ini, and for Windows Vista it's the "IncreaseUserVa" option in BCDedit. By using these options applications can use more than 2GB of virtual address space (generally up to 3GB), and ideally this would be the end of the article.

Unfortunately this is not the case as there are problems on both the application (http://www.anandtech.com/gadgets/showdoc.aspx?i=3034&p=3#) and kernel side of things. On the application side, a common poor programming practice has been to always assume that an application will only be dealing with 2GB of user space; code that makes this assumption will likely error if more than 2GB of user space is actually available. This is avoidable by following proper programming practices, but as a safety precaution even with additional virtual address space allocated to user space Windows still defaults to limiting an application to 2GB. Only finally, if an application indicates to Windows that it is capable of handling more than 2GB, via the "/LARGEADDRESSAWARE" flag, may it have access to any space above 2GB.

As for the kernel, having had up to half of its space taken away must now find a way to live in a smaller space. The (in)ability of any specific system/Windows configuration to deal with this is why the 3gb switch is considered dangerous, seldom recommended, and just generally a bad idea. The biggest culprit here is drivers that run in kernel space. Like applications, they may assume that there's an entire 2GB of address space to work with, except unlike applications this space gets smaller instead of bigger.

Windows' own memory needs can also cause problems with the reduced kernel space. As we mentioned before, space is required for the kernel to do a multitude of things, if a lot of space is required - video cards with a lot of memory are a particular offender here - then everything needing space may not fit in the kernel space. Because there are no strong safeguards against these conditions it may cause a failure to boot or system instability, especially if the culprit is a driver that is well enough behaved to boot. Many modern drivers from hardware (http://www.anandtech.com/gadgets/showdoc.aspx?i=3034&p=3#) vendors that deal with enterprise-level hardware are capable of handling this, many more consumer hardware drivers are not. Stability concerns are the number one reason that breaking the 2GB barrier on a 32bit version of Windows is not recommended.

There is also a second concern however: performance. While an individual application may benefit from more user space in which to work, the kernel now has less space to cache data (http://www.anandtech.com/gadgets/showdoc.aspx?i=3034&p=3#) (as non-obvious as this may seem given all the addresses are virtual) and this can in theory hurt performance.

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There's more in their article but you get the gist. Basically running a 32 bit version of Windows, it may not be worth having more than 3GB of ram

[ReallyDedPoet]

Thanks swdw for the two responses :up:, some good reading there, will print off for reference :yep:

@ Hitman: Yeah, a Motherboard is a possibility down the road.


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[thefretmaster]

thanks for that report swdw. do you think with my new rig im building would it be worth going for the 64 bit edition of windows? for future proofing? or will it just cause more hassle than its worth?
thanks again

[ironkross]

Thanks swdw for the two responses :up:, some good reading there, will print off for reference :yep:

@ Hitman: Yeah, a Motherboard is a possibility down the road.
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I'm waiting till Newegg runs it's Black Friday specials. Last year I built a new rig in the summer and I was astounded when I saw how much money I could have saved with those BF specials in November. Better yet for the same amount how much better my system would be. :damn: