I’ve seen poor quality power supplies fail in spectacular ways.
In my years of IT work, the smell of burnt plastic from cheap power supplies dying was all too common.
For the fortunate ones, only the PSU was toast. For others, it took the motherboard with it.
It can be tempting to grab a $40 power supply and use the extra cash toward a better graphics card or bigger solid state drive.
Don’t do it!
It’s absolutely worth it to spend a little extra for quality when it comes to your power source.
Quick Pick: The Corsair RM650x is quiet, reliable, modular, and has plenty of power for most PC’s.
Watts vs Price – Finding the Right Balance
Power supplies reach as high as 2200W and can cost several hundred dollars.
Fortunately for your wallet, high end power supplies are overkill for most PC’s.
In fact, a 550W power supply is plenty for most gaming and productivity PC’s.
Beyond 750W is typically only useful if you’re running multiple GPU’s or CPU’s.
The best way to ensure you select the right wattage is to use a calculator.
Outervision’s calculator simplifies this. It allows for some “wiggle room” if you make minor changes to your system in the future.
Hit the “Basic” tab on the calculator above, enter your build’s details, and click “Calculate.”
You’ll be all set if you pick any model at or above the “Recommended” wattage given in the calculator.
All devices which run on electricity lose a certain amount of their power input.
If a PSU is 80% efficient, that means 80% of the power being pulled from the outlet is used and 20% is wasted.
Inefficient power supplies have a big impact on a PC.
Power lost to inefficiency is given off as heat.
More heat in your PC means faster fan speeds to expel the hot air. This in turn creates more noise. Too much heat and you’ll run into stability issues.
Also, more electricity is needed to output power to your components. If you run your system several hours a day, or 24/7, it’ll have an impact on your power bill.
Thankfully, power supplies are much more efficient for the price than they used to be.
All good power supplies are given an efficiency rating based on the “80 PLUS” standard.
As the name suggests, to be given this rating the PSU needs to be at least 80% efficient.
Here’s what the different levels look like:
- 80+ or 80+ White: 80% power efficient
- 80+ Bronze: 85% power efficient
- 80+ Silver: 88% power efficient
- 80+ Gold: 90% power efficient
- 80+ Platinum: 92% power efficient
- 80+ Titanium: 94% power efficient
To start with, I recommend no lower than 80+ Bronze.
The price difference between Bronze and a standard 80+ or a non-rated power supply from the same brand is minimal. You’re likely to make up the small price difference over the lifetime of the computer in electricity savings.
Corsair and EVGA don’t offer much in the way of Silver rated units.
80 PLUS Gold is the current “sweet spot” for power supplies.
There’s an efficiency gain of 10% over standard 80+ and 5% over Bronze.
The 80+ Gold units have better quality components and larger fans. All of Corsair’s and EVGA’s Gold PSU’s (except TX series) are efficient enough that the fan isn’t even needed at idle or during basic tasks like web browsing
Cost is a step up from Bronze models, but there are plenty of choices for under $100.
How about Platinum and Titanium?
These models are quite a bit more costly. In most cases wouldn’t spend extra only for the sake of the extra efficiency.
With Platinum and Titanium PSU’s, you do get the best quality components, a full set of features, and high power ratings.
Building a high-end system? You’re typically looking at a $30-70 price increase to go from a Gold to a Platinum/Titanium PSU. They’ll generate a bit less heat and slightly reduce the power draw from the wall.
Like what you see based on the features and power rating? Does the price still keep you within your budget? The improved efficiency of a Platinum or Titanium PSU is a nice added bonus.
Non Modular, Semi Modular, or Fully Modular
Modular in this case means separate cables used to connect the PSU to other components.
Which type of cabling you choose depends mainly on your budget.
Basic power supplies will come with one large bundle of cables hard-wired to the power supply.
This saves a bit on cost, so you’ll see non-modular cabling used in most entry level PSU’s.
There are some downsides to having all your power cables hardwired:
- Unused cables remain inside your PC and take up space
- Air flow can be affected if extra cables are left in the way
- All cables in the bundle are a fixed length
- Each component must be disconnected to remove the PSU
While these are fairly minor issues for most system builders, you might find it worth spending a little extra if cable management is important to you.
For what usually amounts to a small price increase of $10-20, semi modular PSU’s make a big difference in cable management.
The main 24-pin ATX power connector is still hard wired – but since every motherboard needs this cable, you wouldn’t be leaving it off anyway.
Every other cable on EVGA and Corsair semi modular PSU’s is optional.
If you have an M.2 SSD and no other drives, you can skip connecting the SATA cables entirely.
Single GPU systems can leave out the extra PCIe power cable that’s meant for SLI and Crossfire setups.
By using exactly as many cables as you need, you can avoid creating a rat’s nest of wires inside your PC that restricts airflow. Plus, minimizing the cables just looks better.
Semi modular is my go-to choice for value and usability.
High end PSU’s usually are fully modular, meaning every cable (including the 24-pin ATX) is removable.
I don’t usually recommend spending more money just for the sake of upgrading from semi to full modular.
That said, maybe you already have your eyes on a certain model and it’s fully modular.
If that’s the case, there are some nice things about every cable being removable:
- The PSU can be removed for cleaning or replacement with no rerouting of cables
- A longer or shorter 24-pin ATX cable can be substituted
- Custom sleeved cables are more easily made or purchased
Between semi and fully modular, the choice comes down to whether you want to have the best possible aesthetic and cable management inside your build.
Side by Side Comparisons
A 550W PSU is a great choice for the average PC.
The types of PC these power supplies are good for:
- Low to mid-range graphics card
- Air cooling
- Minimal overclocking
- Running a few hours per day; powered off the rest
Let’s look at whether Corsair or EVGA is the better pick at 550W.
Power and Efficiency
Both models here output 550W of continuous (not peak) power. The single-rail 12V power output is identical on both at 45.8A.
They’re both similarly efficient with 80 PLUS Bronze ratings.
Let’s move onto what makes them different.
The CX550M is a semi-modular power supply, meaning the 12V ATX cable is hard-wired.
The 550 B3 is fully modular – the ATX cable is separate should you choose to replace it with a longer, shorter, or custom sleeved cable. The remaining connections are divided up into 5 modular cables rather than 4 on the Corsair, which can help a bit with routing to SATA drives.
The 550 B3 has an Eco mode that can be enabled with a switch on the back. This allows for silent operation under low loads by halting the fan when it’s not needed. This is not possible on the Corsair.
The Corsair on average sells for about $5 less. If Eco mode and better cabling aren’t important to you, I’d save the money and go for the Corsair.
Otherwise, for the small price difference I think EVGA is a better value here.
Overall Winner: EVGA 550 B3
650W PSU’s are fairly popular in gaming PC’s. They allow for some overclocking and can support most any graphics card.
Here’s the type of PC I’d recommend these 650W PSU’s for:
- Mid to high-end single graphics card
- Air cooling or All-in-one liquid cooler
- Mild overclocking
- Running a few hours out of the day, otherwise off
Power and Efficiency
The 650W rating on both models is the continuous power output rather than peak, which is good. The 12V rail output is the same between brands at 54A.
Both have about the same efficiency and were given 80 Plus Bronze ratings.
Features are very similar here.
Both have semi-modular cables. Neither model has an Eco mode for zero-RPM fan operation – look elsewhere if silent operation at idle and low loads is important.
The EVGA 650 BQ is about 25mm/1 inch longer, but houses a larger 140mm compared to Corsair’s 120mm.
Despite this, the EVGA isn’t much quieter. Both models have low noise levels up to about 350W, but get fairly loud under heavier loads.
Both sell for identical prices, and offer 5-year warranties.
A 750W 80 PLUS Gold power supply is my recommendation for most gaming PC’s. They’re a good pick for many workstations as well.
Here’s where I’d recommend a 750W PSU:
- High end single GPU or two mid-range GPU’s
- Air cooling or an AIO liquid cooler
- Overclocked CPU/GPU/RAM
- Running up to 24 hours/day
Let’s see whether Corsair or EVGA is the better pick.
Power and Efficiency
Continuous output (not peak) is 750W as the names suggest for both models. Corsair and EVGA each have single 12V ATX rails at 62.5A and 62.4A, respectively.
Both PSU’s are 90 PLUS Gold rated. The EVGA is slightly more efficient on average, but both perform very well.
These are fully featured power supplies suited for most any PC.
The big difference between brands here is the noise level. The RM750x’s fan profile keeps the fan speed at zero up until around 350W of power draw. From there, it ramps up gradually and is still near-silent. It’s unlikely to be heard over other fans in your PC.
The SuperNOVA does have a zero RPM fan mode as well, but beyond about 150W the fan starts to run. It ramps up pretty quickly from there and unfortunately is quite noisy at 350W and beyond.
The fan on the Corsair is only slightly larger at 135mm vs 130mm; the noise issue seems to be simply due to the fan profile of EVGA’s PSU.
Both models have fully modular cables. EVGA includes six total PCIe power connections (for 3 GPU’s) compared to 4 with Corsair. Keep in mind if you plan to power 3 GPU’s, they would need to be somewhat low-end for this PSU to handle them. Otherwise cabling is similar.
Length of the SuperNOVA 750 is a bit shorter at 150mm in comparison to 160mm on the RM750x.
Both the RM750x and the 750 G3 have excellent warranties at 10 years.
Prices have fluctuated, but typically they’re within $10 of each other, with the Corsair often being slightly cheaper.
Due to the much quieter fan profile, I think the Corsair is the better value here.
Overall Winner: Corsair RM750x
Moving from 750W to 850W gives a bit more headroom for high-end hardware and overclocking.
Power and Efficiency
As with all other Corsair and EVGA models, power numbers are rated in continuous rather than peak power. So, you get the full 850W with both models.
These PSU’s are both 80 PLUS Gold certified so they’re great for 24 hour/day use. Average efficiency is nearly identical.
The Corsair and EVGA both are fully modular and have all the features you’d expect. They’re both compact, with the RM850x being 160mm in length. The SuperNOVA 850 is even smaller at 150mm.
As we saw with the SuperNOVA 750, the fan noise is what sets these two models apart.
The RM850x is one of the quietest power supplies out there whether at medium or heavy load. The EVGA becomes noticeably audible at anything but a low load.
Both models include a 10-year warranty, which is great at this price point.
Prices have actually gone up on the SuperNOVA 850 over time, with the RM850x typically being available for $10-20 less.
Between the louder fan noise issue and the higher cost, I only recommend the SuperNOVA 850 if you have a compact case which can’t fit a 160mm PSU.
Overall Winner: Corsair RM850x
High-end system builders might opt for a 1000W power supply. The number just looks impressive, doesn’t it?
Here’s the type of PC where it makes sense to spend the extra money on a 1000W power supply:
- Up to two high-end GPU’s
- Air, AIO water, or open loop/custom liquid cooling
- Overclocked CPU/GPU’s/RAM
- Running as much as 24 hours/day
Power and Efficiency
Corsair and EVGA both advertise their power ratings with a continuous value. That’s good, because you can use close to the full 1000W instead of being misled by a “peak” rating.
12V rail output moves up to an impressive 83.3A with both models.
Both the Corsair and EVGA are fully modular and compact in size. The Corsair was updated, reducing the length from 180mm to 160mm. The EVGA is shorter still at 150mm.
These PSU’s offer a fanless mode at low loads.
I’m going to sound like a broken record here – but as with the other RMx vs SuperNOVA G3 comparisons, fan noise at medium to high load is much less noticeable on the Corsair. If noise is a concern, this should make the decision easy
10 year warranties come standard for both these models which offers some great piece of mind.
Pricing of the two models was similar at release. However, the EVGA’s price has drifted upward lately and it’s usually $15-20 more expensive.
Combined with the better fan profile of the Corsair, I only recommend the EVGA if noise isn’t much of a concern and you need a shorter 150mm PSU for your compact case.
Overall Winner: Corsair RM1000x
Moving up to the big leagues, we have two powerhouse 1600W PSU’s.
Keep in mind you’ll see better efficiency if you size your power supply appropriately, so don’t go for a 1600W model when 1000W is plenty.
That said, here’s the type of PC you might consider a 1600W PSU for:
- Three to Four high-end GPU’s
- Dual CPU’s
- Custom water cooling
- Extreme overclocking
Power and Efficiency
No messing around with power specs. The advertised 1600W rating is available as continuous power, rather than peak, for both brands.
When you’re pulling a lot of watts, efficiency is important for both your power bill and heat output. Better efficiency means lower operating temps.
Both power supplies have been given the top 80 PLUS Titanium certification. Test results showed both the AX1600i and SuperNOVA 1600 T2 have excellent efficiency, exceeding their ratings in some cases.
12V rail power is bonkers at 133.3A for both power supplies.
These, of course, are fully modular PSU’s. They include plenty of PCIe and CPU/EPS cables to support systems with up to two CPU’s and four GPU’s.
The fan in the Corsair stays still up to about 600W, while the EVGA doesn’t run until 500W. The fan profiles for both models keep them very quiet at everything short of about ~1400W. Noise level should not be an issue with either PSU in normal use.
Digital PSU’s give you access to full monitoring of the power supply via software. In this case, it’s named Corsair Link. You can view output across the individual rails, temperature, fan speed, and efficiency. Very cool stuff if you like to monitor every detail of your PC.
1600W PSU’s can be pricey, but they’re still relatively affordable compared to other high end components such as CPU’s and GPU’s.
There’s a clear winner on value between the two options compared here. The Corsair has been steadily dropping in price, while the EVGA has stayed about the same since release. This puts the AX1600i around $100 cheaper on average.
Add in the fact that the Corsair is a digital power PSU with monitoring features and I think it’s a much better value.
Overall Winner: Corsair AX1600i
We PC builders have it pretty good in terms of warranty.
Most premade computers (and electronics in general) have a pathetic 1-year warranty.
Not the case with power supplies from a reputable brand.
Good PSU’s use high quality components. They often last for the lifetime of the computer. Since they last so long, the makers can afford to provide a long warranty.
Corsair and EVGA both give you a 3-year warranty at the very minimum.
Going with a 650W or higher 80 PLUS Bronze power supply gets you a 5-year warranty on most units from either brand.
Most 80+ Gold PSU’s from Corsair and EVGA include a 7-year warranty or better.
Finally, most 80+ Platinum and Titanium power supplies from either brand step up to a 10-year warranty.
Which brand handles the process better? I’ve had good experiences with both, matching what I’ve seen of their reputations online.
I highly recommend an “Advanced RMA” aka “cross shipping” should you ever need to get a warranty replacement of a critical component like a power supply.
Fortunately, both brands offer this.
You’ll need a credit card for this process. The manufacturer places a hold on your card – usually around the MSRP price of the PSU. This is just in case you never send back the defective power supply.
Corsair/EVGA ships out a new power supply so you can get up and running faster. Once they receive the defective part back, they take the hold of your card and you’re done.
Obviously, your PC can’t function without power. This is a great way to get back up and running without a long wait
Fans and Noise Level
Air cooling has come a long way, and power supplies have benefited greatly.
You won’t find small, noisy, high-RPM 80mm exhaust fans in any of EVGA or Corsair’s PSU’s.
120mm fans are the new standard, with up to 140mm offered in higher-end models.
Larger fans offer more airflow despite lower rotational speeds. As a result, even under heavy load these power supplies don’t generate a lot of noise.
If quiet operation is good enough for you, no offering from EVGA or Corsair will leave you disappointed.
If your goal is to make your PC as silent as possible, it’s a good idea to look at a midrange or better model.
As you move up through the product lines, some important differences can be found.
First, by stepping up from an 80 PLUS Bronze to 80 PLUS Gold or higher PSU from either brand, a zero RPM fan mode is made possible on all except Corsair’s TX and CX series.
When the PC is idle or under low load, the PSU fan doesn’t even spin, which allows for completely silent operation. This is made possible by improved efficiency and reduced heat output.
Beyond 80 PLUS Gold there’s Platinum and Titanium. With these models, heat output is further reduced.
Some of these high-end PSU’s have larger 135mm or 140mm fans to further reduce noise levels.
So, you’ve decided noise level is important and you want to go with a more efficient model with a large fan.
Which brand should you go with?
Between comparable models, Corsair’s power supplies tend to produce less noise. The noise level of most EVGA models is average or below average.
If you truly want the quietest PSU while keeping the price in check, my top recommendation is the Corsair RM series.
There was a time when comparing power delivery specs truly mattered.
It was often recommended to seek out a multi-rail PSU versus single-rail to split up the load and minimize risk to components.
That’s changed since the mid-2000’s.
Now most quality power supplies, even at the high end, are single rail. They have reliable Over Current Protection (OCP) to protect your hardware.
Corsair, which sells both single and multi-rail PSU’s, even states single rail is just as safe.
So worry not – as long as you’re meeting the power requirements of your system in watts, you’ll be fine with today’s single-rail power supplies.
There have been a lot of different standards for PSU’s over time, including EPS, TFX, LFX, CFX, and Flex ATX.
Fortunately PC builders really only need to deal with one or two types: ATX and SFX.
ATX, a.k.a. ATX12V, is considered the standard.
Most desktop cases are mid-towers or full towers, where an ATX power supply is the best choice.
This is the most common PSU type so there are lots of options.
ATX power supplies allow space for large fans for quiet, effective cooling.
While the size is fixed at about 85mm high and 150mm wide, the length of ATX PSU’s can vary.
It’s important to check the specs for your case to find the maximum size PSU that will fit. Some such as the Corsair HX series are 180mm or more in length, which may not fit in more compact cases.
Corsair’s RM series gets my top recommendation in ATX PSU’s for features, efficiency, and very low noise.
SFX, a.k.a. SFX12V, is a small form factor power supply.
These are used in Mini-ITX and SFF cases.
Size is fixed at 63.5mm high by 125mm wide. Certain manufacturers have modified the length (such as SilverStone with SFX-L). Corsair and EVGA stick to a 100mm length, so they’ll fit most any Mini-ITX case.
The trade off to the more compact size is a smaller cooling fan. I recommend an 80 PLUS Gold rated SFX power supply or better to help with efficiency, heat output, and noise.
EVGA’s SuperNOVA GM series is my pick in SFX power supplies. Efficiency is excellent, and noise levels are lower than the Corsair SF series.
Whether you go with Corsair or EVGA, you’ll get a quality power supply with a great warranty.
In general, EVGA’s power supplies are slightly more efficient and compact in size.
On Corsair’s side, many of their PSU’s including the excellent RM series are some of the quietest on the market. Prices on comparable models are often a bit lower as well.