Zalman ZM750-EBT Power Supply Review
Zalman isn't a particularly active company in the PSU market, so it was a nice surprise to see a fresh offering from the company. Zalman's EBT series has four power supplies with capacities ranging from 650W to 1kW. The two smaller models feature semi-modular cabling and are based on Sirfa's HPM platform, while the 850W and 1kW units are fully modular and utilize the Sirfa HPJ platform. Sirfa is an OEM with lots of experience in the lower-end and mid-range categories, so it's a decent choice for the Zalman's EBT line, which targets budget-oriented folks.
All EBT models are 80 Plus Gold-certified and have a single +12V rail. A few years ago, there was a great debate as to whether multiple +12V rails or a single one was better; given the number of single-rail PSUs out there, you can guess the winner. Of course, that doesn't mean PSUs with multiple +12V rails are bad. On the contrary, they offer increased safety. However, you have to properly assign rails to cables and connectors to avoid triggering over-current protection. As a result, we've become accustomed to power supplies with a single +12V rail landing in our lab.
In this review, we're evaluating Zalman's 750W ZM750-EBT. This wattage category is among the toughest, since it includes many capable contenders that are priced aggressively. The ZM750-EBT will have to register a high performance-per-dollar score if it wants to stand out.
We admit that we prefer fully modular PSUs over semi-modular or non-modular ones. However, the first thing that a manufacturer usually leaves out in an effort to lower production costs is modular cables. This PSU has three fixed cables that most PCs need anyway, along with six modular ones. At the time of writing, we found this power supply for less than $100, making it a tempting choice since it undercuts this segment's heavyweights (including Corsair's RM750x and EVGA's SuperNOVA 750 G2 PSUs). If Zalman can get its price even closer to $90, its ZM750-EBT PSU will enjoy a major head-start.
Again, this is a Gold-rated PSU. Unfortunately, Zalman says it can only deliver its full power continuously at up to 40 °C, while the ATX spec recommends at least 50 °C. This isn't a high-end platform though, so we probably shouldn't expect it to endure the toughest conditions (admittedly, most PSUs can't handle a full load continuously at 50 °C).
According to Sirfa, this unit comes with all of the necessary protection features, including over-temperature protection (OTP), which is especially crucial for PSUs with lower temperature ratings like this one. A quality Fluid Dynamic Bearing (FDB) fan cools the PSU's internals and there is no semi-passive mode, though that's probably a good thing. A constantly-spinning fan keeps temperatures down under light loads at the expense of greater stress to the cooler which however won't have a problem with this, since it is equipped with a long lasting FDB bearing. Finally, Zalman looks to have high confidence in this design, since recently upgraded its warranty from five years to seven.
|Total Max. Power (W)||750|
The single +12V rail delivers up to 62.5A, so it will easily feed a couple of high-end graphics cards. The minor rails top out at an ample 120W of combined power, while the 5VSB rail has 3A max current output. It should have no problem charging a tablet.
Cables And Connectors
|Description||Cable Count||Connector Count (Total)||Gauge|
|ATX connector 20+4 pin (510mm)||1||1||18-22AWG|
|4+4 pin EPS12V (660mm)||1||1||18AWG|
|6+2 pin PCIe (510mm+150mm)||1||2||18AWG|
|6 pin PCIe (+510mm)||2||2||18AWG|
|4 pin Molex (460mm+150mm+150mm)||1||3||18AWG|
|4 pin Molex (460mm+150mm+150mm) / FDD (+150mm)||1||3 / 1||18-22AWG|
The main ATX cable is a little shorter than we'd like. In our opinion, it should be at least 55cm long. Conversely, the EPS cable has plenty of length; we only wish there were two of them. The PCIe cables are also long enough. But the distance between the connectors (on one cable with two connectors) is a little short, so you'll have to bend them to reach a nearby PCIe slot. Finally, the distance between the SATA and four-pin Molex connectors is great, though in some cases it'd be nice to have less distance between the SATA connectors.
The number of PCIe, SATA and peripheral connectors is adequate for this PSU's category. We'd just like to see that extra EPS lead, or at least a four-pin ATX12V connector. Finally, the wiring is mostly 18-gauge.
The above diagram shows the ZM750-EBT's cables and connectors, along with their length. As mentioned, three of the cables are native, including the essential ATX and EPS connectors. We think that the third fixed cable, used for auxiliary PCIe power, should be modular, since not everyone needs it. Then again, it's probably a safe bet that anyone with a 750W PSU is at least using a mainstream GPU.
Since this PSU features a single +12V rail, we do not have anything to say about its power distribution.
MORE: Best Power Supplies
MORE: Power Supplies 101
MORE: How We Test Power Supplies
MORE: All Power Supply Content
I'll need to make at least another pass through this article, but failing on +5V ripple under heavy load probably makes this a solid tier-3 unit; I'm not going to run screaming if I see one, but I wouldn't buy it either.
CONS: Ripple • Noisy under stress • Hold-up time • Inrush current • Sleeve-bearing fan • Single EPS connector • Inaccurate PWR_OK signal
Also it must also be strongly pointed out that this unit does not meet ATX specifications.
Hmmm, this one does seem a little worse than I thought at first. Any chance this particular unit had a problem? I'd think ripple could be fixed with a minor capacitor improvement, without adding too much to the price. Hopefully Zalman is paying attention.
One died days after the warranty expired and the other about a month after. I'll give Zalman credit, they made right by me by exchanging both, but it was a painful process.
While I would not recommend these current products, I can at least "tolerate" them in budget builds.
Anyway, I like your power supply reviews, Toms. You go more in-depth than any review site for power supplies (Hardwaresecrets, Johnnyguru).
Considering the same platform performs decently in the Silverstone unit, there's at least some hope that Zalman can go back, adjust a few things, and get a decent budget unit out of this.
Edit: I went back and looked at the Silverstone review. Ripple suppression was really good up to 90% load, then the 5V and 3.3V rails jumped hugely, especially the 3.3V. They did stay within ATX spec, but just barely. The 5V ripple went from 13.1mV at 90% to 40.5mV at 100%, 3.3V ripple went from 14.1mV at 90% to 49.9mV at 100%. Obviously the 3.3V ripple went out of spec at 110% load, as well as one of the crossloads, but that's a lesser sin.