SDHC class 10 UHS-1 card behaving like class 6 card

i recently bought a Sandisk extreme SDHC UHS-1 class 10 card (16 GB one) from flipkart. Soon after opening the package when i tested this card for its performance with Laptops inbuilt card reader, it behaved like normal class 6 card with read/write speeds of around 6MB/s (in b/w 5-6). 

I tested it in several scenarios, with file format change (fat32/exFat, NTFS), with 1.26gb file transfer (from and to card), using CrystalDiskMark 3.0.2. Everywhere it didnt go beyond 6MB/s read/write speed.

card reader used: inbuilt one

Laptop: dell XPS l502x, core i7 2670, 8gb ddr3 ram, 7200rpm hdd…

Please help me on this. Is there any problem with card? or some other issue…

What speed card does your laptops inbuilt reader support?

Cant exactly tell that thing, but it does support SDHC/SDXC cards.
And main thing is this, that even with 4gb sony class 4 card i am getting minimum 8-10MB/s Read/Write speeds.

With 4 gb sandisk class 6 card its 12-15MB/s read/write speeds…
But with 16GB class 10 UHS-1 card it no more than 6MB/s :frowning:

Issue resolved.
Problem was, i do have UHS-1 compatible reader but it was running on default windows 8 drivers.

As soon as i installed its drivers, it worked like charm with R/W speeds of ~40-46MB/s.
when on stock drivers, it wont go beyond 6MB/s. 

When i tested it on an older laptop with SD/HC reader it gave R/W speeds ~ 14-20MB/s.

My conclusion:

UHS compatible reader: actual driver for reader required else it wont even run on minimum speed of 10MB/s for class 10 card. With proper drivers installed you get maxed out speeds (~ 45MB/s)

non-UHS compatible reader: even w/o required drivers, on default windows drivers it gives R/W speeds of min 10MB/s