How Extra Low Latency Memory Came To Existence
When system memory speeds first started escalating beyond DDR400, the main goal for memory module vendors then was to crank out RAM certified for higher speeds that would help overclockers bag the full benefit of pushing their systems to the limits. Overclocking the CPU or the system these days mostly involves manipulating the system bus speeds and tagging it with an appropriate bus-speed to memory clock ratios. Ideally, it would be a 1:1 ratio or otherwise known as synchronous
operation. Any other ratio besides this would incur additional overheads and handshaking protocols to send and receive data. Known as asynchronous
operation, it is best to avoid it if you want to go for optimum system performance. Staunch overclockers know this all too well and since system bus speeds need to be driven up to increase performance and CPU clock frequencies, these users required memory that can run equivalently fast. Hence memory module vendors went full speed from DDR400 to churning other non-official memory speed grades like DDR433, DDR466, DDR500, DDR533 and DDR550.
All this while, semiconductor manufacturers were only producing chips that conformed to the DDR400 specs. Process fine-tuning along the extremely long production run of DDR400 memory parts have resulted in excellent yield these days, so much so that many could effortlessly handle high clock speed operation. To quickly roll out the highest speed grade possible, memory module vendors kept the memory timings very lax. This is why you'll see that many DDR400 modules are rated with average operational timings whereas the DDR500 class and higher would be rated for much slower access timings such as CAS 3.0, 4-4-8.
The Corsair TWINX1024-3200XL extra low latency DDR400 memory in their standard product packaging.
The memory industry has since matured even further and we are now introduced to a new class of speedy memory known as extra low latency memory modules. The concept of low latency modules isn't new and was perhaps first made famous by Corsair when they debuted the Corsair XMS 3200LL series more than a year back. With parameters like CAS 2.0, 3-2-6, they offered speedier access than most normal DDR400 modules rated between at CAS 3.0, 3-3-8 and CAS 2.5, 3-3-6. However, memory like the Corsair XMS 3200LL was tuned for low latency access at default speeds and overclocking headroom wasn't that great those days even if you self assign looser timings at the BIOS level.
Recently, Mushkin sort of revived the low latency memory module segment with hand picked RAM chips suited for extra low latency operation. These offered slightly better stock performance and when traded with average memory timings, they often showed good overclocking potential. Again, this trait was made possible thanks to the matured memory products we have these days.
Following Mushkin's steps, Corsair was the first of the other memory module vendors to strike at this new segment with their XL-series of extra low latency memory modules. Read on to see what else we've discovered while toying with these rare gems.