Another issue besides what Russ mentioned could be a change in the RAM 
timing, or how often and the method the system uses to read from and 
write to the RAM. If the four sticks don't agree between themselves on 
the timing, the system will likely use the slowest stick's timing for 
all four, since all RAM must perform together as a single unit. A faulty 
slot could also cause this as the original poster may have been 
thinking. Trying your old RAM in the switched slots may be a good 
diagnostic tool to compare slots. As for RAM timing, you could use the 
BIOS to override what the sticks ask for and set the timing yourself. It 
is not a task for the faint of heart, and can cause major instability in 
your operating system if the RAM timing is too fast and causes memory 
errors. Take a look in your motherboard manual and on the manufacturer's 
website for tips. Also a good idea in that case to check with the RAM 
manufacturer for acceptable timing settings. Best of luck. :)

Russ Poffenberger wrote:
> Hi Chuck,
>
> I have seen this type of thing before (on Windows 2000 and XP) on different
> systems. While I don't have a full explanation of exactly why this happens,
> I believe it has to do with addressing on a 32 bit processor. Now you may
> wonder why I say 32 bit processor when your processor is 64 bit capable.
> Unless you are running a 64 bit operating system, the processor is running
> in 32 bit mode only.
>
> A 32 bit processor has a maximum addressing space of 4GB, since it uses 32
> bit pointers. While it may seem logical to be able to put 4G of memory in
> such a machine, the reality of the matter is that you can't use the full 4G
> address space to address all the memory. There are other things that require
> address space as well, mainly the hardware devices. This would be all
> peripherals, including disk controllers, network controllers, video
> adapters, etc. It doesn't matter if they are onboard or not.
>
> The devices have top priority in getting address space assigned to them, on
> a typical system this could easily be up to 1G of address space. Since the
> memory and the devices cannot occupy the same physical address space, some
> of the memory must be masked or mapped around the physical devices. I
> believe it is this mapping that results in the slowdown.
>
> In these situations, I have had good luck by installing only 3G of memory.
> You won't miss it since even with 4G of memory installed, you can only use
> at most 3G of it anyway. Another option is to install a 64 bit OS which
> increases the address space by orders of magnitude. However, you may have
> difficulty locating all the device drivers (device drivers MUST be native 64
> bit), some applications may have problems, and those that run may actually
> slow down slightly due to 32 bit thunking required to get them to operate in
> a 64 bit environment under WOW64.
>
> Russ Poffenberger
> [log in to unmask]
>
> -----Original Message-----
> From: Personal Computer Hardware discussion List
> [mailto:[log in to unmask]] On Behalf Of chuck
> Sent: Saturday, October 25, 2008 5:56 PM
> To: [log in to unmask]
> Subject: [PCBUILD] RAM slows Vista
>
>
> My system is slowing down when I add more RAM. I upped it to 4 GB and
> everything slowed measurably. 
>
>  
>
> The system is:
>
>  
>
> Intel Core 2 6400 @ 2.13GHz
>
> Intel DG965OT MB
>
> 2 GB DDR2-533 SDRAM (Hyundai)
>
> NVIDIA GeForce 8800GT 512 MB
>
> Vista Ultimate, SP1
>
>  
>
> At first I added 2 Kingston Value RAM DIMMs with the original Hyundai DIMMs,
> then tried 4 KVR's to make sure it wasn't different manufacturers. I'm
> beginning to wonder if there's not a problem with DIMM slots 2 & 4. As soon
> as I returned to the original DIMMs, everything was fine. Am I missing a
> BIOS setting? 
>
>  
>
> When I have a minute, I'll switch and just use slots 2 & 4 to see if that
> replicates the problem.
>
>  
>
> Thanks for any advice you might have on this.
>
>  
>
> Chuck Finnigan
>
> [log in to unmask]
>
>
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