Author Topic: ram limitations  (Read 1976 times)

0 Members and 1 Guest are viewing this topic.

Offline chrisNova777

  • Administrator
  • Posts: 9073
  • Gender: Male
  • "Vintage MIDI Sequencing + Audio Production"
    • | vintage audio production software + hardware info
ram limitations
« on: March 04, 2017, 10:04:07 AM »

ven if you pack your PC with a full 4GB of RAM, you may only be able to access between 3GB and 3.5GB of it, and a single application is normally limited to using just 2GB. We explain why, and what you may be able to do about it...

With the current low pricing of RAM, lots of musicians are installing more than the typical 2GB in their PCs. Windows Vista 64-bit supports up to 8GB in its Home Basic version, while Vista Home Premium 64-bit ups this limit to 16GB (assuming you have a motherboard that can accommodate this much in its RAM slots!).

However, the vast majority of musicians are still running Windows XP 32-bit (with a small percentage on the newer Vista 32-bit version), and while these both officially support up to 4GB of RAM, in practice Windows will only declare somewhere between 3GB and 3.5GB as available for use, and of this only 2GB will normally be available to a single software application. There are two distinct mechanisms behind these two 'RAM ceilings', so here's some background information that should help sort out the confusion.

Where's My RAM?

First, 32-bit operating systems such as Windows XP Home/Professional/Vista use a memory system based around a maximum of 4GB of address space (two to the power of 32 is 4.2 billion, or 4GB). However, within this memory address space the BIOS allocates some of the addresses to I/O devices, so that a device driver can control the device by reading and writing specific memory locations as if they were normal RAM — but actually those instructions access the device directly.

This 'memory mapping' is a hardware standard that enables software developers to communicate more easily with hardware devices, and is used on most computers, including those running processors from Intel, AMD and VIA, so 4GB 32-bit limitations will affect the latest Intel Core Duo-based iMacs running OS X, as well as PCs running Windows or Linux.

On a PC, most of this hardware stuff gets mapped in near the top of the 4GB address range, so if you install 3GB or less of system RAM you'll normally get to use nearly all of it for running Windows and its applications, as we've all been doing for many years. However, once you install the full 4GB of physical RAM, the addresses used by hardware devices now conflict with some of the higher RAM addresses, so while your BIOS will usually display the full 4GB of RAM, Windows may report considerably less available for system use.

Hardware devices that may eat away portions of the 4GB memory address total include every motherboard device, graphics cards, and other expansion cards, including PCI or PCIe audio interfaces and DSP cards such as the UAD1 and Powercore. You can study the hardware memory addresses for your PC inside Device Manager by selecting 'Resources by type' in the View menu (see screen shot opposite). Windows also commandeers a chunk of addresses for its own internal use.

After installing 4GB of system RAM, the final available figure reported by your operating system may therefore be anywhere between 3.6GB (about the highest figure I've seen reported) and possibly as low as 3GB for a PC stuffed to the gills with hardware expansions.

PC Snippets
Smaller, faster, better? For many musicians, Intel's Q6600 2.4GHz Core 2 Quad, with its 2 x 4MB L2 cache, has been the processor of choice for a long time now (I recommended it, for instance, in PC Notes January 2006), but it now has a serious rival. Intel's Q9300 2.5GHz Core 2 Quad with 2 x 3MB L2 cache features their newer and smaller 45nm technology, which should allow faster clock speeds while generating less heat than the 65nm process used by the Q6600. The Q9300 is already selling widely at similar prices to the Q6600, but manages to out-perform it slightly in most benchmarks, while staying cooler. For those musicians whose motherboard supports this new model (and many don't yet), the Q9300 could become the new favourite.
Intel BIOS update helps musicians: Continuing the recent trend of BIOS updates curing musicians' problems, Intel have released an update for their popular DP35DP motherboard (a popular choice in DAWs) that seems to solve various issues for those who also have an nVidia graphics card, 4GB of RAM and more than one UAD1 DSP card. While this hardware combination apparently works well with up to 2GB of RAM, with 4GB various applications took a long time to launch and screen refreshes became slower. The latest 0437 version ( apparently completely cures these problems. Thanks to SOS Forum user scramble for passing on this information.
Audio Analyser improved: RightMark's Audio Analyser ( is now up to version 6.1.0, adding testing of any MME device in Vista and of any Kernel Streaming output in Windows XP (in the Pro version only), and including various bug fixes and tweaks. The basic version is still free, while the Pro version, with additional ASIO and Kernel Streaming options and GUI skin support, costs £68.90