Japan's Nikkei share average rose on Friday, supported by gains in chip stocks as U.S. peer Nvidia's strong earnings and subsequent share surge continued to lift the sector.

The benchmark index ended the day up 0.37% at 30,916.31, gaining for a seventh straight week, the longest streak in five years.

However, the Nikkei finished well off its highs of the day, fading in the afternoon after entering the midday recess up 1%.

The broader Topix erased its earlier 0.6% rally to end the day flat at 2,145.84, snapping a six-week string of gains.

Japanese stocks have witnessed a volatile week after both indexes surged to post-1990 peaks on Tuesday, followed by sharp retreats.

"Some technical indicators are still flashing overbought signals. So above 31,000, it is easy to think the Nikkei will invite profit taking," said Maki Sawada, a strategist at Nomura Securities.

At the same time, "at these elevated levels for the Nikkei, there are people who want to buy but can't, so when there are dips in shares, they jump on those," she added.

A popular technical indicator, known as the 14-day relative strength index (RSI), has remained above the 70-mark indicating an overheated market all week. It remains around 75 on a scale of 100.

On individual stocks, the Nikkei's performance was very mixed. Seventy of its 225 components rose, while 153 fell, with two ending flat.

Energy was the Nikkei's worst performing sector, dropping 2.45% after crude fell back sharply from a nearly one-month high.

Tech was the best performer, climbing 0.52%.

Chip-making equipment giant Tokyo Electron gained 4.44% and chip-testing machine maker Advantest - which counts Nvidia among its clients - rose 3.92%, building on Thursday's 16% surge.

The two stocks together contributed 128 index points, exceeding Nikkei's total 115-point advance for the day. (Reporting by Kevin Buckland; Editing by Sohini Goswami)