* Datatec stock jumps more than 25 percent
* Synnex to pay in stock and cash
* Deal expected to close in Q3 (Adds comment by Datatec's CEO)
JOHANNESBURG, June 6 (Reuters) - Datatec Ltd unveiled plans on Tuesday to sell its Westcon-Comstor American operations to Synnex Corp, a deal worth up to $800 million that allows the South African IT firm to offload part of a problematic business.
Westcon-Comstor, a distributor of technology and services for network security and data centres mostly in the United States, has been a drag on Datatec's performance in recent months due partly to a troubled software roll-out in Europe, Asia and Africa. The business accounts for more than a third of Datatec sales and profit.
Synnex would also buy 10 percent of Westcon-Comstor operations outside the United States for $30 million with an option to double that within 12 months, valuing the unit at around $1.1 billion.
"We decided it wasn't good for us to monetise those other assets at the bottom of the cycle. They will take a minority interest in the remaining business, which we think has meaningful upside," Datatec's Chief Executive Jens Montanana told Reuters. "But we would entertain a further tie-up with them at some point."
Datatec, which is also listed in London, reported a hefty 66 percent drop in annual underlying earnings last month, weighed down by the tricky deployment of a business management software across Westcon-Comstor operations in Asia-Pacific and Europe, Middle East and Africa regions.
Shares in Datatec rallied as much as 25 percent on the news before paring gains to trade 12 percent higher at 57.40 rand by 1424 GMT. The stock was up by the same margin in London.
For Synnex, the deal hands it one the world's major resellers of Cisco Systems' products and adds data security, wireless routers and video meeting equipment to its portfolio of video graphic processors, hard-disk drives and USB thumb drives.
Under the deal, Synnex will pay $500 million in stock and $130 million in cash and a further $200 million cash payment provided certain financial targets are achieved in the year to end February 2018.
The stock portion of the deal would give Datatec a 10 percent stake in Synnex and Montanana would be appointed to the Fremont, California-based firm's board.
Synnex retains an option to pay all cash, based on the average share price at closing of the deal.
For its fiscal year ended February 28, 2017, the Westcon Americas business generated about $2.2 billion of revenue and about $89 million in core earnings, or EBITDA.
The transaction is expected to close in the third calendar quarter of 2017. The parties have agreed Datatec would pay a break fee of about $25 million if Datatec breaches the transaction agreement.
$1 = 12.7268 rand Reporting by TJ Strydom and Tiisetso Motsoeneng; editing by Alexander Smith and Adrian Croft