TAG RAM Module, got on ebay...

[imported_goku]

I bought a TAG ram module because I have 128MB of ram in my system and since it can only cache up to 64MB of ram, technically I'm suppose to have a pretty big drop in performance (memory bandwidth?) So I installed it, excited to see a huge performance improvement but running sisoft sandra twice, I saw about a 1MB/s performance improvement which apparently improves memory bandwidth efficiency from 24% to 25%.

Anybody have any idea why it didn't improve performance as much as I thought it would or should? I moved the jumper on the motherboard to tell it to cache up 512MB...

Auction

Tom's hardware on the issue.

The look like different IC's but I heard that the module I got was the right specification...

 

[JEDIYoda]

http://www.webopedia.com/TERM/T/tag_RAM.html

"The area in an L2 cache that identifies which data from main memory is currently stored in each cache line. The actual data is stored in a different part of the cache, called the data store. The values stored in the tag RAM determine whether a cache lookup results in a hit or a miss.
The size of the data store determines how much data the cache can hold at any one time. The size of the tag RAM determines what range of main memory can be cached. Many modern PCs, for example, are configured with a 256K L2 cache and tag RAM that is 8 bits wide. This is sufficient for caching up to 64 MB of main memory. If you add additional main memory, however, it won't be cached unless you also expand tag RAM. Some motherboards allow you to add additional tag RAM chips for this purpose but many do not.

For Pentium Pro and Pentium II microprocessors, the tag RAM is integrated in the chipset. Pentium Pros have an integrated L2 cache capable of caching up to 4 GB of main memory. Pentium IIs use a SEC daughtercard for L2 caches and can cache up to 512 MB. "

What I will tell you is usually doubling your ram you will not see a huge increase unless the original value of your ram is quite large....as in 512mb or even 1 gig...

 

[TerryMathews]

TAG RAM was always a very debatable performance boost from what I recall.

You've also got to consider that certain OSes handled the cached RAM issue differently, by addressing the memory space differently. They concentrated their most-used RAM space in the cached areas. I can't recall if it's top down or bottom up that's faster, but Windows after a certain year changes its access methods to deal with this specific issue.

The other is you may be using a processor that does not suffer from this limitation.

Assuming neither of the caveats I listed apply to you, you were only penalized for performance if your system had >64MB RAM, but used <64MB RAM. If you crossed that 64MB barrier in usage, you saw a performance benefit no matter what since RAM>paging, penalty or no.

 

[imported_goku]

Originally posted by: JEDIYoda
http://www.webopedia.com/TERM/T/tag_RAM.html

"The area in an L2 cache that identifies which data from main memory is currently stored in each cache line. The actual data is stored in a different part of the cache, called the data store. The values stored in the tag RAM determine whether a cache lookup results in a hit or a miss.
The size of the data store determines how much data the cache can hold at any one time. The size of the tag RAM determines what range of main memory can be cached. Many modern PCs, for example, are configured with a 256K L2 cache and tag RAM that is 8 bits wide. This is sufficient for caching up to 64 MB of main memory. If you add additional main memory, however, it won't be cached unless you also expand tag RAM. Some motherboards allow you to add additional tag RAM chips for this purpose but many do not.

For Pentium Pro and Pentium II microprocessors, the tag RAM is integrated in the chipset. Pentium Pros have an integrated L2 cache capable of caching up to 4 GB of main memory. Pentium IIs use a SEC daughtercard for L2 caches and can cache up to 512 MB. "

What I will tell you is usually doubling your ram you will not see a huge increase unless the original value of your ram is quite large....as in 512mb or even 1 gig...

So if I added 256MB of ram (total 256), I'd probably see a much larger benefit from using the TAG Ram? How can I tell if the TAG ram is working or not?

 

[imported_goku]

urp