Write Back Cache Modules FAQ

Q. What are write back cache modules?
A. Write back cache modules are installed in the cache sockets of motherboards. On some motherboards, they are socketed, on others they are soldered directly onto the board. Motherboards with these modules are commonly known and advertised as having 256k of write back cache. These modules do not function as cache memory. They are blank modules which contain 0k of level 2 or external cache.

Q. If WB cache modules don't function, why are they manufactured on the motherboard?
A. Good question. Technical support representatives from different motherboard manufacturers have stated a few reasons. First, their motherboards will not function without level 2 cache in the sockets. By installing blank chips, they can trick the MB into thinking there is cache memory installed. Another explanation is that the CPU can use its internal level 1 cache in write back mode with the modules installed. Write back mode is faster than the conventional write through method which increases the performance of the motherboard and CPU by up to 20%. Finally, by installing blank modules in the component feeders at the assembly line, manufacturers lower production costs. Reprogramming robots to manufacture no cache and real cache motherboards can cost upwards of $100,000 including down time.

Q. How important is external or level 2 cache memory?
A. It depends upon which CPU you are using. The cache on older CPUs such as Intel's 486 do not support write back mode. These CPUs need a significant amount of external cache, usually 256k or more, to perform well. Most newer CPUs such as Cyrix's 486/5x86, AMD's SL enhanced 486, and Intel's Pentium utilize write back mode. They do not require large amounts of external cache to perform well. Adding external cache to these CPUs will increase performance however it will not be as significant as adding it to CPUs which use write through mode.

Q. Why did you write this FAQ?
A. The topic of WB cache modules has been very contoversial. People who weren't aware of what WB cache modules are have purchased motherboards thinking they contained 256k of external cache. Once they found out they did not have any external cache, they assumed the motherboard manufacturers and resellers were scam artists, unethical and deceptive. We are committed to our customers and their satisfaction. We want you to be informed of what you are buying before you buy it.

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