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RAM 大小不匹配：CPU-Z 与 BIOS 和 Windows

tag-icon • tag-icon windows-7 memory dual-channel
RAM 大小不匹配：CPU-Z 与 BIOS 和 Windows

最初，我有 4GB 的 RAM（4*1GB），一切运行正常。
几个月前，我的一张存储卡坏了，所以我不得不把它拿出来扔掉。

几天前我买了 2 张相同的新卡并安装好，
所以有 2*1GB 的内存来自一个制造商 (金士顿)，还有 2*1GB 的内存来自另一个制造商 (CEON)。
总的来说，它应该可以让我回到 4GB 双通道。

CPU-Z 报告它们都已安装（CPU-Z 报告），
但BIOS启动时显示3145728K，而且windows也只能识别3GB（系统信息）。

那么...问题出在哪里？

答案1

Due to an architectural decision made long ago, if you have 4GB of physical RAM installed, Windows is only able to report a portion of the physical 4GB of RAM (ranges from ~2.75GB to 3.5GB depending on the devices installed, motherboard's chipset & BIOS).

This behavior is due to "memory mapped IO reservations". Those reservations overlay the physical address space and mask out those physical addresses so that they cannot be used for working memory. This is independent of the OS running on the machine.

引自：http://blogs.msdn.com/b/hiltonl/archive/2007/04/13/the-3gb-not-4gb-ram-problem.aspx

从 CPUZ 数据表来看，主板是 i945。阅读更多：https://forum-en.msi.com/index.php?topic=123711.0

简单来说：Or, a Windows 64-bit computer may show only 7.1 GB of usable system memory when 8 GB of memory may be installed. This is because usable memory is a calculated amount of the total physical memory minus “hardware reserved” memory. http://www.thewindowsclub.com/computer-ram-graphics-card-video-memory

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