Power Consumption And Temperatures
Processor power-saving features were enabled on both of the stock configurations. Both contain the same processor, motherboard, hard drives and optical drive. Both were outfitted with dual channel 8GB memory kits operating at DDR3-1333 @ 1.5V. And unlike the difference between Pitcairn HD 7870 vs. HD 7850, these two Curacao–based GPUs are both fully enabled, the difference being in 3D clocks and default voltage under load. Since the two idled at the same 300MHz Core, 150MHz memory, and at 0.875V, their consumption in that state should be roughly the same. At idle, what basically sets the rigs apart is the power supply and the number (and draw) of the cooling fans.
Under loads, our new Pentium defaulted to a lower VID of 1.065V, where last quarter’s ran 1.075V. Only when we load the GPU would we expect this machine to consume more power; which it clearly does. Yet, our new system also consumes tow to three watts more at idle and under CPU loads. We could perhaps speculate that the Antec VP-450 is slightly more efficient than our current system’s EVGA 500W unit, at least at very low system draw.
While overclocking, I left EIST (Enhanced Intel SpeedStep Technology) enabled this quarter, kept the CPU voltage lower, and ultimately came up 100MHz shy. The result is a reduction in consumption at idle and during CPU loads compared to last quarter. Under full GPU loads, our new system consumed more power. Last quarter’s R9 270 only came up 90MHz shy of matching this R9 270X, but I had ultimately bumped it’s GPU up 0.025V higher to get it there. The math doesn’t seem to quite add up, so we have to wonder how much the efficiency of the two power supplies is coming into play.
It’s worthy of mention that ambient room temperatures during these measurements were about six degrees Celsius cooler this quarter, and subsequently our component temperatures were also lower. We subtract the room temperature, ultimately finding the processors and graphics cores consistently idled about five degrees above ambient. Under loads, our new machine’s Pentium rose two degrees higher. While we didn’t maintain a controlled baseline temperature, there’s still a good chance this increase is from the smaller enclosure and reduced air flow. Milder overclocking at lower voltage then kept our new Pentium running cooler than last quarter’s, despite the smaller enclosure.
By default, MSI’s two 100mm fans were tuned to be quiet, topping out at only 21 percent duty cycle during a 10-minute long Far Cry 3 burn test. Even if the GPU was running within reason, I prefer a bit more airflow when tinkering with GDDR5 clocks. I manually played with the fan finding it quiet up to 40 percent, but clearly audible by 50 percent. I set up a custom profile to ramp up a little earlier, hitting 40 percent just below 70 degrees. This was a perfect blend of noise, cooling performance, and peace of mind, that ultimately kept our overclocked GPU core running much cooler than defaults.
I enjoy gaming through a Logitech 5.1 speaker system. However, I’m prone to immersion loss at the slightest distraction, and a noisy gaming box would have me exclusively switching to my Seinnheiser gaming headset instead. So I found it pleasing that both of these Pentium-based gaming rigs put out relatively low noise levels, and were absence of any annoying fans or coil squeal.