This document provides some frequently asked questions about Sandra. Please read the Help File as well!
Q: Why does it take so long to run the drive/file system benchmark?
A: This occurs when you have a large amount of memory and a rather slow disk. In order to make accurate measurements, the disk and software cache must be swamped by using a test file at least twice as big, as big as possible. Since Windows uses a dynamically allocated disk cache which can be as large 80% of your total memory, Sandra must use a huge file which takes a long time to process. There is no other way since the cache cannot be turned off.
Q: Why does the rating vary between sequential runs?
A: Since the disk cache is dynamic, the size will increase after many disk operations. Since a disk benchmark does only disk operations it is likely that the cache will increase between runs up to the maximum size possible. Generally the bigger the cache the larger the index, therefore the index should increase slightly between runs. When the size of the cache is constant the index should not vary appreciably.
Q: How do I know what ATA mode my EIDE disk is in?
A: Firstly, update to Sandra 2001te or later - and check out the ATA/ATAPI Info module. However, you can also deduce this information from the drive benchmark. The buffered/burst read speed should tell you that information. Thus:
Q: My ATA100/133 drive on VIA Chipset gets only ~70MB/s burst rate and not higher!
A: VIA has released a series of patches to improve performance. Please visit VIA Arena.
Q: My ATA100/133 drive on Intel Chipset gets only ~80MB/s burst rate and not higher!
A: As per errata documents from Intel's website, the 850, 860 chipsets have a PCI issue (Err 5. Sustained PCI Bandwidth) that limits the PCI transfer rates to ~90MB/s rather than ~133MB/s.
Q: Changing the ATA mode does not change the index! Is the benchmark bad?
A: The burst read/write speeds are not included in the index! Thus, unless the sequential & random read/write speeds are limited by the interface the index will stay the same. A slow drive is not faster in, say ATA66 mode than in ATA33!
Q: I've put the drive on a new ATA66/100 controller and I get worse results! What's going on?
A: The controller driver performance is paramount! A fast controller with a slow driver will be outperformed by the built-in controller using Microsoft/Intel drivers. The burst speeds do not influence the index value.
Q: Why are the SMP tests disabled?
A: We haven't found a way to simulate a multi-threaded disk benchmark that would yield proper results yet. Once we do, we'll release an update.
Q: I'm getting Seek out of Bounds, Random Error message! What's up?
A: If your system has more than 1GB of memory, update to Sandra 8.12 or later. The only way to fix earlier versions is to reduce the amount of memory to 1GB or less.
Q: I get abnormally high scores on Windows 2000 on my Athlon system. What's up?
A: Please update to SP2 or later. This resolves a timer chip issue that affects some boards and fast CPUs.
Q: Why is Sandra unable to detect the exact speed of 16X or higher CD-ROMs?
A: The 16X or higher CD-ROMs achieve the rated speed only when the test data file is stored on the outer tracks. If the data file selected by the test happens to be located at inner tracks, the test result will be slower than what the vendors specified. Also due to various overheads you will never get the maximum data transfer from the drive.
Q: I have CD QuickCache and the benchmark crashes when running the CD-ROM benchmark.
A: Try and update to a newer version of the CD-ROM caching software.