" Will 'SD' Card Slot in PC Read SDHC? (Class 4,6,10)


Active Member
I've checked the prior threads, and have not found the answer. In this respect, I am specifying specifics.
1. I presently have a Hp P6370t, Windows 7. On the PC, the card reader states SD/MINI/MMCRS/PLUS/MOBILE.
2. A recent camera purchase allows the use of SDHC. Will the above computer read SDHC? Is this contingent upon the operating system, USB 1, or 2, or the reader itself?
3. I plan on using a class 10 memory card, which displays iiself as UHS-1. Would there be any significance as to class 4, 6, or 10, in terms of 'reading' the memory card?
4. Any and all replies welcome. Thank you very much.


Honorable Member
It's mainly on the OS so I don't think you have a problem but to be on the safe side, ask HP. From Wikipedia:

SDHC cards are physically and electrically identical to standard-capacity SD cards (SDSC). The major compatibility issues between SDHC and SDSC cards are the redefinition of the Card-Specific Data (CSD) register in Version 2.0 (see below), and the fact that SDHC cards are shipped preformatted with the FAT32 file system.

Host devices that accept SDHC cards are required to accept SDSC cards. However, host devices designed for SDSC do not recognize SDHC or SDXC memory cards, although some devices can do so through a firmware upgrade. Older operating systems require patches to support SDHC. For instance, Microsoft Windows XP before SP3 requires a patch to support access to SDHC cards. Windows Vista SP1 also requires a later service pack...

Full article:
Secure Digital - Wikipedia, the free encyclopedia


Active Member
Well, thank you very much. However, I acquired the information. I'm on Windows 7 which already employs FAT32 file system. Some other points of interest relating to memory cards, and usb 2.0 ports.

20-30MB/s for large files is typical for USB 2.0. 30-35MB/s sometimes happens, but is not terribly common, and the more random the access (smaller files, generally), the lower that rate will be, even for the devices that can actually pull it off, and saturate the USB controller. IE, pulling off a video should generally be faster than a directory of typical photos. Many times, the card readers themselves will be limited, more-so than just the USB interface, so if you find a PC-integrated reader is only getting 10MB/s, don't be quick to blame USB.

480Mb/s is the rate the bus actually operates at, including all overhead. USB also is half-duplex, which causes some slow-downs. If you want to be confident you'll get > 25MB/s or so, get a USB 3.0 card reader, and plug it into a USB 3.0 port.

So, there is no issue if you can interpret the above. Thank you for your assistance.

Also note that most cards are only rated for sequential writes, so reads of all kinds can and will vary, though reads are usually the same speed as writes in the worst cases.
* Buy the faster rated CF cards since they do help with data throughput speeds on the device itself.

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Honorable Member
It was just because of the line: "By comparison, the older "×" rating measured maximum speed under ideal conditions, and was vague as to whether this was read speed or write speed." that I didn't want to mention read speeds as a reply to your question.

But great information. Thanks.


Active Member
Thank you very much.

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