As Compal Electronics and Wistron are competing aggressively over orders for Acer's upcoming 8- and 10-inch entry-level tablet devices, sources from the upstream supply chain are concerned that the orders may hurt the ODMs' profitability as the models will only provide limited profits for the makers.

Acer, Compal and Wistron have declined to comment about the orders.

The sources believe the entry-level tablets' success in the market will prompt more brand vendors to join the competition and the launch of Hewlett-Packard's (HP's) entry-level Slate 7 tablet at Mobile World Congress 2013 (MWC 2013) was just the start, as both Lenovo and Samsung Electronics reportedly plan to release their low-price tablets in the near future.

In 2013, 7- and 8-inch tablets together will account for 45% of total shipments. 10.1-inch models will account for about 20%, the sources estimated.

As market demand is gradually turning to tablets from notebooks, ODMs have become aggressive about tablet orders. Foxconn Electronics (Hon Hai Precision Industry) may ship more than 100 million iPad devices in 2013, staying in the lead of the tablet manufacturing industry, while Pegatron Technology with iPad mini orders, will compete against Quanta Computer with Google's and Amazon's tablet orders, for the second place.

Compal is expected to ship 8-10 million tablets in 2013 with orders from Acer and HP, while Wistron is estimated to supply six million units in the year, triple those in 2012.

Acer's 7-inch Iconia B1-A71 tablet is projected to reach shipments of 2.5 million units in 2013 and the company also plans to release a second-generation model at the end of 2013 with shipment expectations of 1.5 million units.