Flash Memory Performance - CF vs SD; Readers compared

You likely used a digital camera this past year with either a CompactFlash (CF) or Secure Digital (SD) memory card. We've recently upgraded our digital cameras so I decided to probe "which is faster, SD or CF cards?" And "which card reader is the fastest, USB 2.0 or FireWire 800?"

The new Nikon D80 features the smaller Secure Digital (SD) memory "wafers." That was a bit of a bummer since we already had CompactFlash (CF) cards for the previous D70S model (which we still have and use). I was impressed with the speed of the SanDisk Extreme IV CompactFlash in our previous testing, especially when used in combination with the SanDisk Extreme FireWire 800 Card Reader. However, the SD cards are not available in the Extreme IV version from SanDisk. Nor is there such a thing as a FireWire reader for SD cards.

Does it really matter what you use? How do the different cards and readers compare in the "real world"? We had accumulated 116 photos on the D80's memory card totaling 399MB. I decided to time how long it took to copy them to a folder in our Pictures directory.

In the first graph below, we compared a 2GB Extreme III SD card in the SanDisk Extreme USB 2.0 reader to a 2GB Extreme IV CF card in that same reader as well as SanDisk's FireWire 800 reader. We also tested a 1GB Extreme III CF card in both readers. The Mac Pro was our test "mule." (We measured almost identical times on the MacBook Pro C2D.)

In the second graph, we illustrate how much faster USB 2.0 runs on the Mac Pro (and other Intel Macs) versus the Quad-Core G5 Power Mac (and other PPC Macs).

Obviously, USB 2.0 is optimized for Intel Macs. You are better off using FireWire 400/800 on a PowerPC based Mac.

INSIGHTS

1. The SanDisk Extreme IV CF card benefits from the speed of the SanDisk Extreme FireWire 800 Card Reader. In combination they "blow away" all other CF or SD memory card/reader pairings when transferring photos to any Mac with a FireWire 800 port. In QuickBench tests, we measured over 38MB/s when reading files from 2MB to 10MB size, so SanDisk's boast of 40MB/s is credible.

Plus, when we connected the SanDisk FW800 Reader to a FireWire 400 port on the Mac Pro, MacBook Pro, or Quad-Core G5, we got the same times that we got with the FireWire 800 port! Huh? Yes. The same cannot be said of regular FireWire 400 card readers like the Lexar CF FireWire 400 Card Reader which ran no faster than the USB 2.0 reader on our Intel Macs.

2. If you are using the SanDisk Extreme USB 2.0 CF/SD Reader, the SanDisk Extreme IV CF card transfers photos no faster than the SanDisk Extreme III CF or SD cards. If you only have a FireWire 400 or USB 2.0 reader, the Extreme IV card is a waste of money -- unless you have a FireWire 800 port and purchase the FW800 reader. If you have an Extreme III CF card, it will NOT transfer faster on a FW800 reader. You must buy the Extreme IV CF card to take advantage of the SanDisk Extreme FireWire 800 Card Reader's transfer speed.

If you have Secure Digital (SD) cards, there is no way to make them transfer faster since they are not available with any faster rating than 150X and there is no such thing as a FireWire 800 SD reader.

3. The SanDisk Extreme USB 2.0 CF/SD Reader transferred photos 31% faster to the Mac Pro and MacBook Pro than it did to the Quad-Core G5 Power Mac. Obviously the USB 2.0 port implementation is more efficient on the Intel Macs (since, "duh," Intel invented USB).

However, the G5 Power Mac transferred the photos via the SanDisk Extreme FireWire 800 Card Reader and Lexar CF FireWire 400 Card Reader at the same speeds as the Mac Pro. So when it comes to FireWire readers, the Intel and PPC Macs have virtually identical performance.

4. Not all readers are created equal. The newer Lexar CF FireWire 400 Card Reader transferred photos twice as fast as our old SanDisk Ultra ImageMate FireWire 400 CF Card Reader (which is no longer made). We found the same to be true when we compared bargain priced USB 2.0 readers with the SanDisk Extreme USB 2.0 CF/SD Reader.

5. Speed ratings on memory cards are not a reliable method of choosing flash memory cards. We tested a 150X rated OCZ 2GB SD card against the 133X rated SanDisk 2G SD card. The OCZ should have been 13% faster. In reality, the SanDisk was 13% faster.

CONCLUSION
If you use CompactFlash cards and feel it's taking too long to transfer photos to your Mac using a USB 2.0 reader or FireWire 400 reader -- and you have a FireWire 800 port, you will be able to transfer those photos at least 2.4 times faster than the fastest alternative if you use a SanDisk Extreme FireWire 800 Card Reader in combination with a SanDisk Extreme IV CF card.

If you use Secure Digital memory cards, you are don't have a speedy FireWire 800 option -- at least for now.

You can order the Extreme IV CF Cards and Extreme Card Readers direct from SanDisk.

Other World Computing sells SanDisk products. I'm sure they can get the Extreme cards and readers.