(Reuters) -U.S. stock index futures fell on Friday as caution dominated the mood ahead of a highly anticipated inflation report that could influence the Federal Reserve's September interest-rate decision.

Contracts tracking the tech-heavy Nasdaq fell the most, with personal computer maker Dell and chipmaker Marvell down 5.8% and 13% after their quarterly forecasts missed expectations.

The dour reports came a day after AI leader Nvidia said geopolitical uncertainty clouded its China market forecasts, although strength in overall results and bullish comments from CEO Jensen Huang calmed worries of an imminent slowdown in demand for artificial intelligence infrastructure.

The relief helped the S&P 500 and the blue-chip Dow close at record highs on Thursday. The benchmark index and the Nasdaq were on track for their fourth straight month of gains.

Nvidia lost 1% in premarket trading after logging its biggest daily drop in more than a week in the previous session.

The focus now shifts to a report on the Fed's preferred inflation gauge - the Personal Consumption Expenditures index (PCE) - expected before the bell.

Economists polled by Reuters expect the index to stay steady at 2.6% in July from the month before. Excluding volatile items like food and energy, however, the index is expected to rise 2.9%, up from 2.8% in June.

"Recent inflation developments offer little reassurance," said Seema Shah, chief global strategist for Principal Asset Management.

"While July's inflation report wasn't alarmingly strong, underlying signals point to building price pressures amid higher trade tariffs."

At 05:43 a.m. ET, Dow E-minis were down 154 points, or 0.34%, S&P 500 E-minis were down 21.5 points, or 0.33%, and Nasdaq 100 E-minis were down 117.5 points, or 0.49%.

Traders are pricing in an 84.2% chance that the Fed could lower borrowing costs by 25 basis points in its September meeting, according to data compiled by LSEG, further anchored by Chair Jerome Powell's dovish comments at Jackson Hole where he acknowledged labor market weakness.

Late on Thursday, Governor Christopher Waller, a candidate for the central bank's top job, said he wants to start cutting rates next month.

Still, some analysts have said overall data suggests a resilient economy with little signs of U.S. tariffs fully filtering through into prices yet.

On Friday, however, the U.S. tariff exemption for package imports valued under $800 ended, raising costs for businesses and, in turn, consumers.

Attention this week was also on U.S. President Donald Trump's tussle with the central bank.

Governor Lisa Cook filed a motion that declared Trump's effort to fire her was unlawful and seeks to bar the Fed from taking steps to remove her pending further litigation. A hearing on the motion is due at 10 a.m. ET.

Long-term Treasury bond yields rose on worries that a politically influenced Fed could reduce the credibility of U.S. debt. Bond yields move inversely to prices and higher yields weigh on riskier stocks.

Among others, global economy bellwether Caterpillar lost 2.9% after raising its annual estimate for tariff-related costs.

Cybersecurity company SentinelOne rose 6.8% after raising its annual revenue forecast. Apparel maker Gap lost 1.8% after reporting comparable sales below estimates.

(Reporting by Johann M Cherian in Bengaluru; Editing by Devika Syamnath)