So I picked up a just-released ASUS 7790-DC2OC-1GD5
the other day, and one of the features that's long appealed to me about the 7000-series Radeons is "ZeroCore". Since I switch off my monitor overnight while leaving my PC on (to run automatic backups, routine scans, etc.), it makes sense for the video card to shut itself down as much as possible in that situation.
But there's not much feedback here on ZeroCore, so I thought I'd kick off a topic on it with a few of my experiences so far. To start with, here's my system power consumption (not including monitor) in various idle states, measured at the power socket with my Belkin energy meter.
Desktop a few mins after boot: 49W
Notepad (maximised, empty window): 48W
Firefox (maximised, displaying static web page): 49W
Display off, ZeroCore activated: 39W
And here are the "annoyances" I've encountered so far - I titled them in bold to more easily distinguish them, not to suggest they're definitively true:Not fully compatible with GPU monitoring apps
Running GPU-Z minimised with 'continue refreshing in the background' checked would apparently cause ZeroCore to cycle on and off, or something along those lines (I observed the video card fans initially cycling off and on under this condition). Power consumption would be reduced, but only by a few watts - e.g. from 49W to 46W instead of 39W.
In the case of SpeedFan, I needed to remove the tray icon using Windows' notification area settings to allow ZeroCore to function. The GPU temperature and fan speed readings would also freeze after ZeroCore had been activated (they'd display -999C and 0 RPM respectively), so I had to remove those.It's dependent on display power management
Switching off the display via its power button wouldn't activate ZeroCore - it only kicked in when Windows power management turned off the display. If I manually switch off the display first, ZeroCore will still subsequently activate based on the power management timer.The display had to be static (watch out for those blinking cursors)
A notepad window or a login prompt with a blinking cursor are some forms of screen activity that prevented ZeroCore from activating. Scheduled tasks that involve display activity can deactivate it, and I've had to modify one of my backup scripts which displayed results a notepad window (with blinking cursor) and prevented ZeroCore from activating again after the task was done.Power consumption increased after ZeroCore
This is a really strange anomaly I encountered - most of the time, after coming out of ZeroCore, idle power consumption increased in some cases, with the most dramatic being the extra 12W consumed while displaying the desktop (including when the desktop is partially visible behind non-maximised foreground windows):
Desktop a few mins after resuming from ZeroCore: 61W
Notepad (maximised, empty window): 51W
Firefox (maximised, displaying static web page): 47W
Weird, isn't it? According to GPU-Z, the GPU gets stuck at 0.988V when displaying the desktop, instead of 0.825V pre-ZeroCore. This is reproducible and persists indefinitely until the system is cycled with a reboot or suspend, undoing the efficiency gains provided by ZeroCore. Note that I have a static desktop - there are no widgets or anything, just a static wallpaper and shortcuts.
EDIT: This issue appears to be fixed
in more recent drivers I just found and tested (the 7790's drivers are separate from the main Catalyst downloads at the moment, which I didn't realise before so I used ASUS' ones).May not work over HDMI or DisplayPort
This isn't a personal observation, but a claim I repeatedly encountered while troubleshooting - there were many reports that ZeroCore won't function over HDMI, and a couple that it didn't function over DisplayPort (with none confirming it did). I'm using a single display connected with a HDMI (video card) to DVI (monitor) cable, and it works in this configuration.
I'd appreciate any observations from others about ZeroCore.
P.S. I suspect a few of you might ask about the noise levels of the ASUS 7790, but I can't offer anything more than a subjective "it's really damn quiet at idle". Techpowerup has reviewed the card and they seem better than most sites in the noise measurement department.
Here is the fan speed range as reported by SpeedFan:
0%-10%: 1084 RPM
20%: 1110 RPM (this is the card's default idle speed)
100%: 3281 RPM
The fans are 0 RPM when ZeroCore is active