Introduction

It's summer time and PCs are working in warmer environments than they're used to. With our PSU buyer's guide for the summer season we want to focus on some of the quality power supplies we've tested (or are in the process of testing). It's important to pay attention to heat, particularly if you're in a home without AC, as increasing environmental temperatures can create problems. Users may not want to get the absolute quietest power supply available if it's going to be in a relatively hot environment, as these may create instabilities due to a lack of sufficient cooling. Of course, if you do have AC or live in a colder region, we'll have some silent and near-silent recommendations.

In terms of recommendations and budgets, we need to clarify a few things before we begin. We pretty much won't even touch power supplies that cost less than $50; it's possible to get an okay power supply for a truly budget price, but you will get a lower efficiency model and you're taking something of a risk. We don't feel the risk is excessive, so for truly entry-level systems you can go ahead and look at the ultra-cheap options out there (i.e. cases that come with a PSU). However, keep in mind that lower efficiency means your initial savings will almost certainly disappear with higher power requirements over the coming months and years.

As an example, consider a budget system that requires 80 W of power in order to function. Using an 80% efficiency power supply means that you will draw 100 W from the wall; a 70% efficiency power supply will require around 115 W. If you leave the system on all the time, you will be looking at somewhere near $15 per year spent on power due to PSU inefficiencies. An 80 W system is also pretty low end; if you're running a midrange system that uses more like 160 W, your yearly power costs will obviously double. Likewise, it's possible to get an 85% efficiency power supply and cheap options might only be 65% efficient, again resulting in a doubling of savings.

Having set the stage with that example, our budget power supply offerings will start at $50 and ranged up to around $85. $85 on a "budget" power supply may seem unreasonable, but we are more interested in quality than strict dollar amounts, and so our categories will be based on how much power the various PSUs are able to deliver more than cost. Once you begin to focus on quality power supplies, a corollary to the above is that higher output options will cost more money, so our recommendations may have some overlap.

Budget Recommendations

Since our last PSU buyer's guide, little has changed on the lower end of the market. We still won't recommend products that carry far overrated ratings of 500W where the reality is that it's more like a 350W power supply. Our selections therefore focus on high-quality models with a reasonable cost - typically under $75. For the European market we focused on good power supplies under 50€.

Enermax Pro82+ 385W and 425W - $73-86

Enermax had an impressive launch this year with the Pro82+ and the Modu82+. We saw first samples in Las Vegas in January and tested four models later on. The delivered performance gave us no choice other than to award both series the AnandTech Gold Editors' Choice Award. Both series deliver very stable power and very good efficiency - up to 86% with 230VAC. With all of the tested models we were able to stay above 82% efficiency from 20% load onwards. The noise levels were equally impressive, since these units remained essentially silent up to a load of more than 50% of the maximum rated output. On top of the good performance, Enermax keeps the price within reach even for users with moderate budget.

Corsair VX450W - $70

The price of Corsair's power supply remains somewhat high, with little change since our recommendation in December last year. This doesn't change the fact that the CMPSU-450VX is still a very good power supply and worth every penny. With its price of around $70 it outperforms every other power supply with wattage in this field. We saw smaller voltage drops from this PSU but the overall efficiency and performance is very good, making it ideal for midrange systems running a single graphics card.

Seasonic S12II 330 & 380 - $54 & $64

Both of the Seasonic S12II models rated at 330W and 380W fall under the 50€ barrier. They have been popular throughout the world and they are actually the reason Seasonic increased their sales in Europe. Seasonic currently sits in the top three brands in Germany together with be quiet! and Enermax. Seasonics quality has always been good, and even the small incident with incompatibility with a few motherboards didn't really weakened their position in the market. There were small voltage drops during our tests last year, which is common with Seasonic power supplies, but everything was well within specs. The acoustics are also very nice, ranging from 22 to 25dB(A). The price made these PSUs hot sellers, starting at only $54 for the 330W version, which is enough for most PCs.

be quiet! Straight Power 350 & 400W - 40 & 47€

be quiet! for many years has been the unchallenged number one in Germany. They achieved this with good prices, good quality, and customer service offers that to this day no other company can match. The Straight Power series is our last recommendation in this field with a good price for the 350W and 400W versions. These units are just starting to sell in the US and there are only a few models available right now. What makes be quiet! products special in Germany is the 48 hour exchange service, where a postal guy brings a new power supply to the customer and takes the broken one with him within 48 hours of your call. The company also offers a 3-year warranty, which is also unusual in Europe. Several US-based companies like Corsair and OCZ surpass the 3-year warranty with 5-year warranties, but they still don't offer a 48-hour exchange guarantee.

Midrange Recommendations

In the midrange/moderate PSU market, we have power supplies rated at 500W to 650W and a price range of $82 to $202. Most power supplies in this field aren't that expensive, however - the high $202 models are from Antec's Signature series, which we introduced not long ago. Most of our midrange PSU recommendations are a more reasonable $125 or less.

Enermax Pro82+ & Modu82+ 525W - $110-$133

The Enermax Pro82+ and Modu82+ are again worth a look, this time courtesy of the 525W model. The prices of the 525W unit start at $110 for the Pro82+ version, and the modular version bumps the price to $133. The $23 difference is quite a bit, considering you can hide the extra cables between optical drives, so we'd give the nod to the Pro82+ version instead of the modular offering. If you simply prefer modular cables and are willing to pay more, however, both options perform the same in testing.

Cooler Master Silent Pro 500W - 82€

Unfortunately, Cooler Master cannot currently sell this power supply in the US market due to a lawsuit from Ultra against everyone with cable management. Europeans however can enjoy the Silent Pro series, which is also available with an M for modular. We will be introducing this power supply very soon, and we have already completed testing of our first samples. We are very pleased by the performance and for the first time Cooler Master went to Enhance for a lower range power supply. The side-trip paid off and Cooler Master created one of the coolest products this year. Not only does it maintain a noise level of 17dB(A) up to a high level of load, but it also has a very attractive price of 82€ for the 500W version. That puts it only a few Euros above competing products from Enermax and Corsair, with better performance particularly in the noise arena.

Corsair CMPSU-520HX 520W- $115

The Corsair HX series has sold well since the "memory company" first introduced it, paving the way for their later models. The HX520 not only brings rock stable rails, but it also comes with a very good efficiency and very low acoustic noise throughout the operating range. The EU and the US prices are very attractive, helped by the fact that this PSU has been available for several years. It can still compete with all the new power supplies today, which is impressive. We will be providing a review of this series soon, even though Corsair does not even promote it anymore.

Antec Signature 650 - $202

Antec's Signature series has not been around long, and somehow it hasn't managed to make its presence felt in the market. In Europe, the 650W version is the only one available, even though Antec has an 850W version that we already tested. We've received word from Antec that the 850W model will be available very soon in Europe, and until then users will have to "settle" for the 650W version - which honestly won't be much of a difference. To find out exactly where the differences lie, Antec sent us one of the lower wattage versions and we will have a review up soon. Antec included many features in this series, which they largely developed on their own. For $202 this power supply is anything but cheap, and we hope that with higher availability the prices will drop. The high price does bring some exceptional quality, however, as you can read in our review.

High-End Recommendations

There's always a lot more room for companies in the high-end market, where profit margins are significantly higher. Of course, many times the only difference between competing products seems to be the price tag. In theory, the goal of a PSU is to deliver power to the system components, but they are also becoming something of a status symbol. "Hey - check out my 1200W PSU! It could power a small third-world country. (Yes that makes me awesome!)" None of this is really important if all you care about is delivering stable power to demanding components, but if you want a top-quality PSU design you will need to spend more money. Simply put, you're not going to get equivalent quality of components in a 330W PSU as in a 1200W PSU, because the former faces a lot of competition from inexpensive, marginal units. Put another way, if it costs $100 in materials just to make a top-quality design, you're pretty much forced to build 600W or higher PSUs.

One complaint that we have on many lower rated PSUs is that there aren't enough cables to run high-end computers. If you want 9800 GTX SLI, you will need a minimum of two 8-pin PEG connectors and two 6-pin PEG connectors - or three each if you want triple-SLI. We asked PC Power & Cooling at the beginning of the year if they could make us a power supply rated far below 1000W but with a maximum of connectors to show that it's possible to fire up a triple-SLI system and 15 hard-drives together. At CES PC Power founder Doug Dodson gave us our special version which performed extremely well in our later tests. (We have not been able to test this PSU with the latest 280 GTX cards, however, and given their insane power requirements it could very well be that 1200W PSUs have a place in running such setup.)

PC Power & Cooling Turbo Cool 860W - $215

The Turbo Cool series was never intended to cater the mass market. The prices are high but PC Power & Cooling delivers a product worth every penny. The internals seem like they come from another planet, since they don't look even close to what we see with other manufacturers. On top of that, PC Power uses a DC-to-DC conversion for the lower voltage rails, which is similar to what we discussed in our last Silverstone review. The performance was excellent, with only 2.8mV ripple on the 12V rail. The efficiency at medium load was over 88% with 230VAC, which is one of the best results we have seen so far. We continue to see more and more power supplies with high efficiency scores, but they frequently top out around 85% or 86%; hopefully we'll see more competitors with equal results soon. Of course noise levels weren't that great on the Turbo Cool, with a minimum of 23dB(A), but PC Power likes to think first about the health of the power supply and low noise is typically a secondary concern. The price of a little more than $200 is well worth it if you're after quality, and the price in Europe is about the same in Euros (200€) and therefore much higher when the exchange rate is factored in. It would be great if prices in Europe were closer to the US equivalent.

OCZ EliteXStream 800W - $155

The EliteXStream series is for the hardcore enthusiast and we are surprised about the price, especially for the 800W version. At $155 it is clearly ahead of the competition even though it offers a few watts less in maximum output. Our tests showed this series was designed well, with average efficiency among the high-end units (86% 230VAC, but only 84% on 115VAC). The noise output ranks among the higher end of the options, similar to PC Power, which is good for the system health but not for the ears. For hotter climates, however, that may be just what you need; it has been designed to handle high temperatures and withstood our 50°C stress test without any problems.

Silverstone Decathlon 700W - $174

We just tested this power supply that was supposed to be one of the quietest options in the market. We weren't disappointed, since the Decathlon 700W only generated 22dB(A) at the highest load possible. The efficiency wasn't best in class, but with up to 85% 230VAC Silverstone has to be ashamed of - a 10% difference in efficiency is meaningful; one or two percent not so much. The price of $174 is rather high unfortunately, and even though Silverstone felt it would drop over time we haven't seen much change to the price during the past month or two. However, while the OCZ may be less expensive and provide more power, $20 more to dramatically reduce noise output could be a useful investment. Also, we'd be cautious about running high loads on this power supply in hotter environments, as the noise levels directly correlate with higher temperatures.

Corsair HX1000W - $226

Corsair did well to take their time with this 1000W unit. They brought a very nice product to the market, using an older design from our friend CWT that continues to perform well. There are many cables included in the box for use with the cable management system, so users will be sure to have enough cables and connectors on this unit to fit any need. It was also the first 1000W power supply certified by NVIDIA for triple-SLI use. The output stability and quality is very good and didn't drop at all during operation. The efficiency is again "average" among our top-end units, coming in at up to 86% with 230VAC and 84% with 120VAC. Unfortunately, the fan turns reaches maximum RPMs at only 80% load, which makes for a noisier environment. Again, this is for the best in terms of power supply health, and it will be better for warm climates, but at more than 35dB(A) we would rate the acoustic output as falling on the high-end of noisy. The good news is that under low and normal loads, the noise will not be too high so users of less extreme systems won't have as much to complain about. The $226 price tag is a lot to pay for a power supply, and since availability is still not very good we have hopes that the price will drop in the near future, but for a good 1000W PSU the price is tolerable.

Antec Signature 850W - $242

This PSU isn't even available and it's already recommended. From what we in our testing of this power supply, it is worth the high price. The price difference between the two versions isn't that large, so you'll have to decide whether you want to spend $200 for a 650W unit or $40 more for additional 200W. Our decision would be to go for the higher version if you're spending that much, since we never know what new parts will come out for PCs. In general, 650W should be enough for all but the most power-hungry setups, but here a 20% increase in price for an additional 30% power suggests the upgrade is worthwhile. Hopefully with better availability the prices will also drop, and perhaps the gap between the two versions will widen making the lower power 650W unit more viable. In terms of performance, the Antec Signature leaves an impression since it comes with many new features including the DC-to-DC conversion for lower voltage rails. Yes, we saw minor drops in voltage regulation but they are all well within specs. The efficiency is one notch above most other units, reaching up to 87% and 230VAC; more importantly, it stayed near 87% over a larger portion of the output curve. Another plus is that this power supply is very difficult to hear up to around 650W of power output, qualifying as a true silent unit.

Zalman ZM850-HP 850W - $175

Zalman sent the 850W and 1000W units to our test lab and both perform very well. We liked the heatpipe cooling, and we were pleased to discover it really helped dissipate heat and is not only there for aesthetic reasons. The lower heatsink temperatures resulted in a very low noise level, which stayed low up to very high power outputs. We measured a maximum of 23dB(A) even with higher loads, which makes the 1000W model the quietest PSU above 800W. The efficiency of up to 87% with 230VAC is also one step above many competitors, and from 170W up to 750W of power draw the efficiency stayed above 85% which is great. We saw some voltage drops, but these were well within specs. The one caveat is that this power supply is very long and will have problems with many "normal size" cases. If you are interested in this PSU, make sure your case can support the length of 210mm (around 8 inches). With a price of $175 this unit is definitely worth a look; the 1000W model costs about $55 more, making the 850W model the preferred version for most users.

PC Power Silencer 750 Quad 750W - $125

We have added our favorite power supply of 2007, since we saw a very nice price drop from $199 down to $140 during the last six months. This PC Power unit still has virtually everything a new model would bring and we can still recommend users to buy it. Its performance a year ago was very good, with very little in the way of voltage drops and efficiency reaching up to 87%. The noise levels are higher than some of the competition, but the maximum output of 750W keeps it lower than some of the other PC Power options, topping out at 30dB(A) under maximum load. The price of $140 is already a major selling point, but we're now seeing a few models coming in as low as $125 - and there's a $25 mail-in rebate on top of that! That makes this a high-end PSU with a moderate output price, and we recommend this product to anyone with the need for a good quality power supply (as long as prices and inventory stay where they're at). PC Power & Cooling also offers this model in blue, though we still prefer the bright red.