Автор работы: Пользователь скрыл имя, 25 Декабря 2012 в 22:03, реферат
The southbridge on AMD mainboards houses the AMD SATA controller, AMD USB2 controller, the controller for the legacy PCI bus and hosts and several single lane PCI express connections. It also connects to the onboard audio chip on the mainboard and the onboard network controller(s) on the mainboard as well as the legacy I/O controller chip which houses things like the old parellel printer port, serial port and PS/2 mouse/keyboard connectors. The way these items are wired up to the southbridge is either via an internal PCI bus connection or an internal PCI express connection. To the operating systems these devices appear the same way as when they would be on an expansion card in a PCI or PCI express slot.
The bottom line
So again, which is fastest? The answer to this is: it depends. If an application reads a lot of different memory locations in a short amount of time the 1333 memory in the example will allow the application to run faster than the 1600 example. If an application needs to read a lot of subsequent memory locations starting from a specific location, the 1600 will be faster. How applications behave is notoriously difficult to predict and what makes it even harder is that part of the memory performance will always be obfuscated by the CPU cache.
In any case, like with all things hardware, there are no free rides. A lot of 1600 memory might seem cheaper than some 1333 memory but if you dive down to the real issues you are likely to find that the lower the actual CAS Latency, the higher the price will be :-)
CPU Cache revisited
Remember the previous page in which CPU cache size was mentioned? If not, flip back to the previous page and read up on that. In essence, the previous page states that the larger the CPU cache, the less your CPU will need to access the main memory. Given what we have just learned on memory this means that the larger your CPU cache is, the less your memory data rate will matter. However, every time the CPU cache needs to read from your main memory, chances are good that it will need to read from a new memory location. CAS Latency is thus as important as it ever was!
Информация о работе Форм-факторы материнских плат (Basic PC architecture)