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I teach PC and Server system architecture to PC engineers...
All the above comments are valid. In laymens terms, If your PC has sufficient RAM, it should be able to render without paging parts of RAM to the hard disk. (a process called 'virtual memory' which allows your PC to pretend it has more RAM than it really does, by dynamically swapping (paging) data between RAM and a special file on the hard disk (Swap file or Paging file))
Virtual memory is useful, as it allows you to run more programs simultaneously, than you have real RAM to allow. However, it's disadvantage is that that it is incredibly slow compared to reading and writing data in true RAM, because it involves using the hard disk (very slow mechanical device).
Windows will always maintain a Paging file, even though it will not use it intensively until you start running out of real RAM.
Win XP will run in as little as 64MB of RAM, but with huge amounts of paging to virtual memory, which literally cripples your PC! 128MB is better, but as soon as you start running application programs you are back to paging and everything slows down again... The trick is to avoid the paging process at all if you can help it. 256MB should allow windows XP to run swiftly, along with a consumer type of video editing package (Close any unnecessary programs though). Adding more RAM above and beyond this will allow XP to use that spare RAM to cache it's system files, and allow for a slightly speedier response of windows, but will not improve your render times.
As an alternative example, If I were editing high quality scanned photographs instead, I may have a scanned image of a photograph in RAM occupying 300MB, if I had scanned it at say 600 dots per inch. if I were then to apply an effect to the photograph, most image editing applications would then wish to take up to another 300MB of RAM to apply these changes and allow for undo. I now therefore have to consider having around 1 Gigabyte of RAM in my PC to avoid paging in this instance.
A friend of mine bought a budget Celeron based PC with 128MB of RAM (£500), and it was a dog! I treated him to a 250MB RAM upgrade last Christmas, which cost £25. This increase in total RAM to 384MB vastly improved the performance of his PC through reducing paging, knocking over a minute off his boot up time, and allowing much smoother response when running multiple applications. if you think of cost, a spend of 5% of the value of the PC absolutely transformed the users experience, and reduced annoyance and frustration in using a slow, unresponsive PC, saving hours of his valuable time!
The component that will have most effect on render times (assuming your PC now has sufficient RAM) is the CPU. the faster the better. the disk subsystem has less of an impact on rendering, as the amount of video data being streamed to and from the disk is quite low compared to the transfer speed of today’s hard disks.
There is no need for RAID arrays (disk striping in particular) for your home PC, and in many instances this will actually slow your PC down. (Some of you may not agree with this, but I assure you I can prove it (very technical issue))
A cleaner solution is to have a separate hard disk to your windows drive, and use this purely for you video content. If you can afford it, go for two additional drives instead, one for your video source material (captured footage hence where to render from) and one for your target material (where to render to).
It is very important to regularly defragment all of your hard disks, as this prevents your drive heads from dashing about all over the place trying to retrieve parts of a file. (Slows everything down significantly, and incurs wear).
Some people partition a hard disk into two or more sections, each with it's own drive letter. Whilst this reduces fragmentation of files when compared with using a single partition for everything, it reduces the performance of the drive significantly. The first reason for this is that the drive heads have to constantly seek between two different partitions on different parts of the drive (slow, and incurs yet more wear) particularly true in your application when you are likely to be reading a video file from one partition, then rendering it and saving it to the second partition... Your drive heads will be doing overtime! The second reason that performance is slowed is that your hard disk has some RAM built into it (typically 2 or 8MB these days) to act as a cache between the interface cable and mechanical disk parts of the drive. If you write a small file to your hard disk, it actually first gets blasted into the hard disk's cache very quickly, then the hard drive commits it to the surface of it's disk platters in it's own good time. The same goes for reading. The RAM is used to read ahead a little. If you start to open a file from the disk, it will cache the next bit of data found on the disk in it's RAM assuming that this is the bit you will want next. A partitioned drive being used for multiple read/write activities between partitions can not use it's RAM cache effectively, and this slows performance further.
Yes some video editing apps can use your video card's GPU to render special effects. this can further improve performance if you have a suitable video card.
Finally, a dual CPU PC can further improve render times, but only if your video application is multi-threaded (many are). The cost of dual CPU hardware tends to be cost prohibitive though, as this type of solution is really targeted at small business server solutions.
Stick to a quickish Pentium 4 or Athlon/Athlon64 system if you can afford it, with at least 256MB of RAM, or ideally 512MB. Two or more hard disks are advisable as suggested above, but SATA offers negligible performance benefit over IDE, so save your money. Enjoy!
Craig.
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Hybrid Mode
