Apple's possible move from Intel x86 chips to ARM processors for its MacBooks is feasible, but not practical over the next few years because of technical and performance issues, analysts said this week.
In the short term, ARM processors won't be able to deliver the performance MacBooks draw from x86 chips, these analysts said. Apple currently uses ARM processors for the iPhone and iPad, and more power-hungry Intel chips on its Mac computers.
"It's possible that Apple is looking at ARM, particularly for specialty devices like MacBook Air where thin and light is critical," said Jack Gold, principal analyst at J Gold Associates. "But as a mainstream chip to power all the Macs, I'd be surprised if they went that route."
Media reports last week suggested that Apple would move MacBooks from x86 to ARM processors over the next few years.
However, analysts said x86 processors will continue to remain a staple for Macs, while a move to ARM could increase the support and validation cost for hardware and software.
Moving from Intel to ARM would be a "big risk for relatively little gain", said Real World Technologies analyst David Kanter in a study published this week on the company's website.
"ARM microprocessors are designed for lower performance and unlikely to match x86 performance in the next few years," Kanter said.
Some technical issues may also prevent Apple from moving to ARM on Mac laptops, Kanter said.
Apple this year introduced new MacBooks with the high-speed Thunderbolt interconnect, which was designed with Intel. The interconnect is not yet available for ARM, and Intel may have little motivation to make it available for a rival architecture, Kanter said.
ARM currently has virtually no presence in the PC market. ARM processors are used in netbook-like devices called smartbooks, which have not sold well.
However, an IDC analyst predicted last week that ARM would capture a 13 percent share of the PC microprocessor market by 2015, as a result of Microsoft's decision to make Windows available on ARM processors.
Intel chips based on the x86 architecture implement complex instruction sets and wide cache for performance, while ARM focuses more on power consumption and has little experience with complex instruction sets, Kanter said
"Emulating x86 on ARM is eminently feasible, but there is a performance tax. An ARM microprocessor would need to run faster and more efficiently than current and future x86 designs to avoid losing performance and power efficiency for generic software," Kanter said.
Even if Apple decides to move to ARM on MacBooks, it will have to continue using x86 on its high-end Mac Pro desktops, which are based on Intel's Xeon server chips. That could split the Mac product line, and increase the cost required to support different hardware and software.
Replacing Xeons would be pretty difficult, Gold said. ARM processors are not designed to run high-end applications on Mac desktops.
With laptops and desktops running on different chips, maintaining a full OS for two different architectures could be a nightmare, just as Microsoft may find as it ports the upcoming Windows 8 to ARM, Gold said.
Porting the OS is no trivial issue, but is possible with sufficient testing and redesign, analysts said. Apple shifted from the Power to Intel's x86 architecture, in the middle of the last decade, during which the software transition was smooth, said Roger Kay, president of Endpoint Technologies Associates.
"The transition could be as smooth as the one from Power to x86, which arguably went pretty well," Kay said.
ARM has not expressed interest in the PC market, saying its priority remains in designing low-power processors for mobile devices. But the ARM ecosystem is emerging fast, and it makes sense for ARM to develop high-performance processors to compete with x86, Kay said.
Going by history, Apple doesn't hesitate shifting architectures, and the company would be willing to move to ARM if it can deliver the performance required by Macs, the analysts said.
In September, ARM announced the Cortex-A15 processor design, which will first appear in tablets and smartphones starting in late 2012 or early 2013. The processor, based on a 32-bit design, can run at speeds of up to 2.5GHz and stretch to 16 cores. However, it lacks some capabilities available on x86 chips, such as 64-bit addressing and a large memory ceiling.
If ARM processors are able to cram more CPU and graphics cores to execute tasks simultaneously, they could outperform x86 chips, said Jim McGregor, chief technology strategist at In-Stat. Future ARM processors will have more cores and higher clock speeds to execute tasks in parallel, McGregor said.
Chip makers such as Nvidia are already showing how dedicated hardware accelerators can take the load from the processor for specific tasks like video decoding.
"They can and are becoming even more parallel and you can fit many more of these cores on a single chip than an x86, or limit the number of cores and run it with much lower power while reducing the cost of the cooling solutions," McGregor said.
If Apple moves to ARM on its MacBooks, one of the top reasons would be to unite all its devices under a single architecture, but that likely won't happen in the short term, analysts said.
"In general, x86 will continue to have a performance advantage, but this advantage can be mitigated through the normal course of development and some hardware trickery on the ARM side," Endpoint's Kay said.