EVGA Z75 SLI VRM
The EVGA Z75 SLI uses a beefy all-digital VRM, and comes in a 7+2+1 phase configuration for the CPU. Below is a detailed look at how everything is laid out:
To maintain 100% full digital control over all voltages, EVGA are using three digital PWMs by CHiL:
- 1) CHL8328 7+1 Digital PWM
- 7 phases to VID (main CPU voltage) shown in red
- 1 phase to VAXG (integrated GPU) shown in blue
- 2) CHL8325a 5 phase Digital PWM
- 2 phases going to VCCIO (memory controller, PCI-E controller, etc) shown in yellow
- 3) CHL8325a 5 phase Digital PWM
- 2 phases going to VDDQ (DRAM) shown in green
As you can see, EVGA did not cheap out here; to have a fully digital power system, they had to use three PWM controllers. VDDQ needs its own PWM since the power comes from the main ATX power header instead of the 8-pin header.
All four of the main power planes use International Rectifier IR3553 power stages. These chips are rated at 40A each at 20 Celsius, and include the driver and MOSFETs in one package. These are similar to the “Driver MOSFETs” or “DrMOS” made by Vishay, which are commonly used by Gigabyte. Those chips are known to get very hot under load, so it will be interesting to see if we run into the same issues with these.
You may have noticed that the VID and VAXG planes (red and blue) are using strange looking capacitors – they look similar to the “Hi-C” caps used by MSI on their “Military Class” products. These are actually patented POSCAP capacitors, made by Sanyo in Japan, and are very high quality. Although not all power planes use these, the most important ones do.
The Z75 SLI gets full credit for a powerful VRM, including over 315 amps to the CPU. This is more than enough to overclock Ivy Bridge on air, provided you keep the voltage down and temperature in check. If you are to the point where you are running at more than 1.5v, you may run into power delivery limitations. For instance, running the CPU at 1.5v and letting it get to the point where power starts leaking, you can easily reach 200W or more to the CPU. That’s 300 Amps right there, which is pretty close to the limit of this VRM. It’s not something you’ll need to keep in mind unless you are REALLY pushing it. Or if you are brute-forcing your CPU to hit higher clock speeds. In that case, it’s your fault… This board was built for overclocking in a gaming system, not world records with LN2, so it is excellent for its intended target.
EVGA Z75 SLI Component Tour
Let’s take a tour of the Z75 SLI, looking at every chip that makes it tick. I think you’ll agree that this is a better use of your time than cutting and pasting the specs onto a page. Besides, motherboards are always fun to look at, so here we go:
We’ll kick things off with everyone’s favorite motherboard mascot – the Realtek Crab~! This time he’s on an ALC898 audio codec, alongside some capacitors to smooth out the sound a bit. This is an 8 channel chip (plus 2 stereo inputs for line-in and mic), rated for 110 dBA output. It supports DTS and Dolby Digital decoding, but not in real time. The Z75 SLI does not include audio managers like Dolby Home Theatre or X-Fi.
Tucked away right beside the CMOS reset switch is a tiny Nuvoton NCT7802Y hardware monitor. This provides the Z75 SLI with temperature and voltage measurement, as well as fan controls for up to three PWM fans and two DC fans. We’ll take a closer look at these features when we look at the BIOS and software. The Z75 SLI uses the NCT7802Y’s fan controller for the CPU fan only.
The Nuvoton’s monitoring capabilities are supplemented by this Fintek F71889AD Super I/O chip. In addition to providing the Z75 SLI with potential legacy connections such as Serial, printer ports, etc (the board only actually uses the PS/2 keyboard port), it also adds extra hardware monitoring and fan controls.
The Z75 SLI’s single ethernet port is handled by this Marvell 8059 Ethernet controller. There isn’t much to say about it now, as we’ll be looking at performance later.
There are actually two Marvell chips on board – This 9172 hosts a pair of SATA 3.0 ports internally, while another 61xx hosts a pair of SATA 2.0 ESATA ports on the rear panel. We usually recommend using these only as a last resort when you run out of Intel ports, or for ESATA or optical drives. But we’ll take a closer look than we used to starting with this review.
Right below the DIMM slots, you’ll find this interesting header. It’s actually called “EZ Voltage” and as you can guess, it’s a series of contact points allowing you to easily read voltages with a multimeter. It’s not labeled at all, so you’re completely on your own to figure out what each point is for. Most people won’t use this, especially since the board already has good voltage monitoring hardware built in.
Finally, we come to the BIOS chips, and there are two of them which can be selected manually with a jumper. Interestingly, only one of them is permanently attached, allowing for easy replacement should something go wrong.
On the next page, we’ll take a look at the BIOS and any software EVGA includes with the Z75SLI