Why can't I get advertised transfer rate from card reader?

I bought a SanDisk ImageMate All-in-One USB 2.0 Reader/Writer.
On the box it advertises up to 34Mb/sec.

I also have a 4GB Kingston Elite Pro 133x (advertised up to 20Mb/sec) and a 4GB Lexar Pro 233x (advertised up to 35Mb/sec)

Both are formatted as NTFS. I'm using a 2 month old laptop (AMD Turion X2 Dual Core, 64-bit, 4GB Ram, Vista, USB 2.0) No other apps running.

Fastest write time is ~12Mb/sec and fastest copy/move time is about 14Mb/sec on the Kingston and 16Mb/sec on the Lexar.

These are close to half the advertised rates. What's wrong? Can anything be done to improve transfer time? Format the card differently? In camera vs. laptop formatting?

I wouldn't worry if it was off by a few Mb/sec but losing half/third seems like way too much.

Well, the key words are "up to". A lot could depend on the file size, how fragmented the card or hard drive is. Is the HD a 7200 or slower 5400 unit? How large is the cache?

Some things like the drive speed are beyond your control, but defragmenting both the card and HD may help.

Advertised maximums are theoretical on all networking and storage product. Maximum real world speeds on ethernet is 60% of spec. So on your gigiabit network, you are going to get 600Mb tops. I have some high end servers with 320MB/s SCSI disk drives in them. I have yet to see 1/4 that speed in real world usage.

There is marketing speeds, and there are real world speeds. Those speeds you are getting are very fast and likely the top end for real world speed.

Nortelbert wrote in post #7411951
Well, the key words are "up to". A lot could depend on the file size, how fragmented the card or hard drive is. Is the HD a 7200 or slower 5400 unit? How large is the cache?

Some things like the drive speed are beyond your control, but defragmenting both the card and HD may help.

yup. "up to" is just a guarantee that you won't get any more than.....it's an oooold advertising trick .

ed rader

ed rader wrote in post #7411999
yup. "up to" is just a guarantee that you won't get any more than.....it's an oooold advertising trick .
ed rader

I can understand if it's advertising something like MPG. Sometimes I drive like an ape on the throttle so poor economy is to be expected. And if this were on an old computer with USB 1.0 where slower speeds would be expected, I wouldn't have a problem.

Other thought, isn't there a max speed on USB 2.0 and could that be holding it back?

tkbslc wrote in post #7411975
There is marketing speeds, and there are real world speeds. Those speeds you are getting are very fast and likely the top end for real world speed.

If that's on the faster end and that's the best I can get then I'll be happy with it.

And don't forget, "up to" could be referring to any single slot on the reader, not necessarily the CF slot; possibly the SDHC slot. Also the USB ports (and cables) for your laptop and the hub, if you're using one, will make a difference.

I just noticed too that it says it was tested with a SanDisk Extreme IV card(45Mb/sec)

Jeff wrote in post #7412768
Other thought, isn't there a max speed on USB 2.0 and could that be holding it back?

the theoretical max for USB 2.0 is 480Mbps.

tkbslc wrote in post #7411975
Advertised maximums are theoretical on all networking and storage product. Maximum real world speeds on ethernet is 60% of spec. So on your gigiabit network, you are going to get 600Mb tops. I have some high end servers with 320MB/s SCSI disk drives in them. I have yet to see 1/4 that speed in real world usage.

There is marketing speeds, and there are real world speeds. Those speeds you are getting are very fast and likely the top end for real world speed.

Those numbers are not right.

http://sd.wareonearth.​com/~phil/net/overhead​/

I've worked on fiber networks that were much more efficient than 60%, if TCP/IP were that inefficient ISP's would go out of business. Not knowing your infrastructure or topology I will hazard no further guesses, but if those numbers are accurate something is wrong somewhere.

USB overhead is comprised of a number of factors, USB chipset, processor speed, cable length, media, reader... for all that your USB performance is pretty good. Remember speeds are marketed one way, but your computer will typically report them another.