How To Tame High Idle Power Draw On Intel's Arc Desktop Graphics Cards
There wasn't a lot of chatter about this when the reviews went up, but Intel's Arc graphics cards suffer from relatively high power draw for their performance. That's true not only under load, but also when idle. While even the monstrous GeForce RTX 4090 will drop down to less than 25 watts at idle, the Arc A770 can pull as much as 45 watts.
Now, 45 watts isn't a ton of power, but it's a fair bit to let go to waste for no reason at all, especially in this era of ever-increasing power bills. Perhaps as an attempt to get out in front of the issue before it blows up into a controversy, Intel has published an article explaining how to resolve the problem. Well, perhaps "work around the problem" is a more accurate description.
There's a screenshot of the relevant portion of Intel's article, although the company goes into greater detail about why these setting changes are required for Arc. Essentially, what it boils down to is that the cards won't clock down to their lower power settings unless the PCIe interface does so itself. Intel requires you to enable PCI Express Active State Power Management and ensure that L1 substates are enabled before Arc cards will stop slurping power without a load.
We haven't tested these changes ourselves to see what impact it has, but in so doing, we think it's important also to test the impact on I/O performance. You see, these changes to the BIOS and operating system won't just affect your Arc graphics card, but also any other PCIe devices. That is likely to include NVMe storage on most modern systems, and may also include things like discrete USB controllers or network adapters.
It's entirely possible that enabling ASPM won't have any effect on these devices. After all, ASPM isn't supposed to reduce the performance of devices that are actively operating. Past experience tells us that it's likely to have an impact, though. Other power-saving measures, like core parking, have shown time and again to hurt performance in unexpected places.
Intel also says that Arc cards may draw more power than otherwise when high-refresh-rate displays are connected, but that's completely expected. NVIDIA struggled with an issue for years where cards with connected high-refresh-rate displays wouldn't power down at all, causing much higher idle power usage than just 45 watts. That problem seems to have been corrected in recent GeForce drivers, but we don't fault Intel for struggling with it.