* Q2 GDP up 3.0 pct vs prior est of 2.6 pct
* August ADP data shows biggest monthly increase in 5 months
* H&R Block down after bigger-than-expected quarterly loss
* Indexes up: Dow 0.01 pct, S&P 0.05 pct, Nasdaq 0.30 pct (Updates to open)
Aug 30 (Reuters) - The S&P and the Dow opened little changed on Wednesday as investors focused on data that showed stronger-than-expected U.S. economic growth, helping offset worries over President Donald Trump's latest tweet on North Korea.
Gross domestic product increased at a 3.0 percent rate in the April-June period, the Commerce Department said in its second estimate.
The upward revision in the second-quarter data from the 2.6 percent pace reported last month reflected robust consumer spending as well as strong business investment.
Adding to the positive sentiment, a report from payroll processor ADP showed that U.S. private employers added 237,000 jobs in August for its biggest monthly increase in five months, above the 183,000 jobs expected by economists.
The strong data could strengthen the Federal Reserve's case for another rate hike this year.
Chances of a rate hike rose to 37 percent from 32 percent after the data, according to CME Group's FedWatch tool.
The ADP report comes ahead of the more comprehensive government payrolls data for August on Friday.
Investors are also keeping an eye out on the ongoing tensions between the United States and North Korea after Trump dismissed any diplomatic negotiations with North Korea, saying "talking is not the answer," a day after Pyongyang fired a ballistic missile over Japan.
The "U.S. has been talking to North Korea, and paying them extortion money, for 25 years. Talking is not the answer," Trump tweeted on Wednesday.
"We suspect the North Korea problem, although not yet causing a rush to exit will eventually take a negative toll on the markets," said Peter Cardillo, chief market economist at First Standard Financial.
Also on the radar is Trump's first speech specifically on tax policy later in the day. The speech, officials said, would be about "why" reforming the tax code was needed, not about "how" to reform it.
"Trump's outline of tax reform today is likely to be well received by the markets," Cardillo said.
At 9:42 a.m. ET (1342 GMT), the Dow Jones Industrial Average was up 2.2 points, or 0.01 percent, at 21,867.57, the S&P 500 was up 1.23 points, or 0.05 percent, at 2,447.53.
The Nasdaq Composite was up 18.79 points, or 0.3 percent, at 6,320.68, on gains in Apple and Amazon .
Eight of the 11 major S&P sectors were lower, with the energy index's 0.52 percent fall leading the decliners.
Crude oil prices slid, while gasoline futures hit their highest since mid-2015 on Wednesday as flooding and damage from Harvey shut over a fifth of U.S. refineries.
Tropical Storm Harvey made its second landfall in Louisiana on Wednesday, pouring down more water after setting rainfall records in Texas.
Among stocks, shares of H&R Block fell 7.2 percent to $27.29, the top S&P percentage loser, after the tax preparation service provider reported a bigger-than-expected quarterly loss.
Chico's FAS declined 7.41 percent after the apparel retailer forecast gross margin declines and a bigger drop in full-year comparable sales.
Dycom Industries fell 5.71 percent after the broadband fiber installer's forecast missed expectations.
Declining issues outnumbered advancers on the NYSE by 1,435 to 1,087. On the Nasdaq, 1,152 issues rose and 1,130 fell. (Reporting by Sruthi Shankar in Bengaluru; Editing by Sriraj Kalluvila)