Owners of Apple's 27-in. iMac have reported that the firmware update released earlier this week has not solved their flickering display problems, according to Apple's own support forum.
Apple issued the firmware update Monday, saying that it was designed to "address issues that may cause image corruption or the display to flicker" on 27-in. iMacs equipped with the ATI Radeon HD 4670 and 4850 graphics cards.
But users continue to complain on Apple's support forum that the update was no fix for them.
"Flickering/tearing has been occurring occasionally (once a day maybe), so I downloaded and installed the firmware update, but I'm still experiencing the same problem," said a user identified as "gjdhks999" today on the massive thread dedicated to the flickering issue. That thread lists more than 1,600 messages and has a view count of more than 263,000, making it the most-read of those on the iMac forum.
"I, like everyone else, has verified that the firmware update does NOT fix the issue," added Joe Liu on the same thread. "Strangely enough I seem to be able to recreate the issue by doing the following things: 1. Use computer all day. 2. Turn off overnight. 3. Turn on in morning -- within 90 minutes it's flickering."
Some users, in fact, claimed that the firmware update had made their iMac start flickering. "Ran the firmware update last night and had no flickering," said Patrick Seguin on Tuesday. "Today I have flickering galore."
Others, however, said the update had at least reduced the flickering. One, dubbed "smakus" on the thread, guessed that the firmware update had reduced the clock speed of the ATI's card's graphic processor. "The power supply and video card have drastically reduced in temperature," smakus reported. "The flickering is still present, although it happens once, then immediately goes away, whereas before, it would flicker then steadily escalate, getting worse and worse until the blackouts started. This tells me one thing. They most likely de-clocked the video card to produce less heat, or are somehow ramping it down until the power is needed."
Display issues have plagued Apple's 27-in. iMac desktop computers since the new machines debuted Oct. 20. Users have reported cracked screens, a yellow tint in part of the display, irritating flickers and black bands.
The problems prompted one Canadian Web developer to collate the complaints on a specially built Web site, and may have been one of the reasons why Apple slapped a two-week shipping delay on 27-in. iMacs earlier this month.
That Web developer, Scott Pronych of Nova Scotia, who created the Apple iMac (Fall 2009) Issues site to track the problems, has added a "Flickering after Firmware Update" category to the site. As of mid-day Wednesday, Pronych had logged 26 accounts of the firmware failing to fix the flickering problem.
"I think it's too early to say at this point whether the firmware update works for most people or not," Pronych said, "but it certainly does not fix the issue for everyone."
Pronych also noted the scarcity of reports from people who have one of the newest-built 27-in. iMacs, those tagged as being part of the batch assembled in Week 51. "Either Apple hasn't shipped very many of the Week 51 iMacs or they've solved the problems," said Pronych. "It's impossible to tell." Still, he speculated that it was the former -- that Apple put a shipping hold on all iMacs -- because there were very few reports, either of flaws or that everything was fine with the machine.
Pronych, who had to return one 27-in. iMac because of a shattered screen, recommended that people wait to purchase the model until Apple has the problems sorted out. "Hold off, that's what I would tell anyone thinking of a 27-in iMac," he said. "I don't know if even Apple knows what the problem is [with the flickering]. If the firmware update actually doesn't work, then the problem is more serious, something in the hardware."
His second iMac has not exhibited the flickering screen others have noted, but Pronych remains concerned. "I'm kind of worried that it may show symptoms down the road, long after the warranty has expired," he said.
Apple's online store continued Wednesday to show a two-week shipping delay for all 27-in. iMacs.
Apple has declined to answer questions about whether the 27-in. iMac delays were caused by an unacknowledged hardware glitch, but last week the company issued a statement apologizing for the iMac's availability problems, and put the blame on sales. "The new iMac has been a huge hit and we are working hard to fulfill orders as quickly as possible," the company said in a statement.
Gregg Keizer covers Microsoft, security issues, Apple, Web browsers and general technology breaking news for Computerworld. Follow Gregg on Twitter @gkeizer, send e-mail at email@example.com or subscribe to Gregg's RSS feed .