Rosewill Photon-1200 PSU Review

Today, we evaluate Rosewill's Photon-1200, manufactured by Sirfa, featuring fully modular cabling, Gold-rated efficiency and a high watt-per-dollar ratio.

By Aris Mpitziopoulos
published

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Performance, Performance Per Dollar And Noise Ratings

Performance Rating

The following chart shows the total performance rating of the PSU, comparing it with other units we have tested in the past. To be more specific, the tested unit is shown as 100 percent, and every other unit's performance is shown relative to it.

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Compared to more advanced and more expensive platforms, the Photon-1200 PSU doesn't stand a chance. It registers a much lower overall performance score. The truth is that if you spend $30 to $40 more, you can get a much better-performing unit, which might also be significantly quieter than Rosewill's noisy offering.

Performance Per Dollar

The following chart may be the most interesting to many of you because it depicts the unit's performance-per-dollar score. We looked up the current price of each PSU on popular online shops and used those prices and all relative performance numbers to calculate the index. Note that all of the numbers in the following graph are normalized by the rated power of each PSU. 

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Despite its good price, a low performance score doesn't allow the Photon-1200 to achieve a higher performance-per-dollar ratio.

Noise Rating

The graph below depicts the cooling fan's average noise over the PSU's entire operating range, with an ambient temperature between 28 and 30 °C (82 to 86 °F).

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The Photon-1200 manages to surpass even Seasonic's noisy units, which use even smaller-diameter fans. This is quite an achievement, and we mean this in the most negative way possible. 

Aris Mpitziopoulos
Aris Mpitziopoulos
Contributing Editor

Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.

7 Comments Comment from the forums
  • MasterMace
    Sirfa has produced too many poor units in the past to get any leeway or benefit of the doubt. It failed 80 Plus Gold in the hotbox at 100% load.
    Reply
  • boller
    I have a good perspective on that ripple thing: just finished repairs of a PC power supply and when I was measuring ripple I found it was out of whack (300 mV pp). After some investigation I found out that measuring ripple is a tricky thing. Tom's description on how they do it is very incomplete. Eevblog guy spent an entire episode on ripple. In my case I had to do this: limit oscilloscope bandwidth 20 MHz, instead of the grounding clip use that spring attachment and measure loaded PSU at the last cap before leads. Ripple went down from 300 to 48 mV pp.
    Reply
  • Aris_Mp
    First of all you don't just hook a scope on a PSU's output and measure ripple else you will catch huge spikes, like in your case, which will totally alter the measured result.

    Secondly most users aren't interested on how I do things (and even if I elaborated on all the procedures I follow only a fraction of them would understand them) but about the final result. For me the most important is to explain what ripple is and how it can affect the components of a system.

    Thirdly. You don't have to watch Dave to see how ripple is measured properly. You can check on the ATX spec which includes the ripple measurement procedure. I follow all guidelines of the ATX spec so if you need to see how I measure ripple or load regulation just take a look at them. In any case the following scheme will show you how to measure ripple on a PSU.

    Reply
  • boller
    No need to be defensive, I was just pointing out that your _description_ is incomplete, not that you do it wrong. Although it would be nice for you to place a note over there saying that actual procedure involves some additional caps and an honest to god differential probe (!)
    Reply
  • Aris_Mp
    I just replied to your concerns. No need to think that I am defensive because clearly this is not the case with me.

    I already stated that I don't mention how I measure ripple since among others all of us reviewers have to follow the ATX spec procedure. There is no point in repeating the whole ATX spec from the moment that anyone can download and read this spec with a simple google search.

    Besides these two caps (which are already pre-installed on the fixtures that most of us reviewers have. There also present on loaders like the Sunmoon ones) and the good quality probes you also need to isolate all external noise that can pass from the PSU's EMI filter. In other words you need to provide "clean" power to the PSU. Personally I do this with a Chroma AC source and in the near future I plan to get a online UPS with some extra circuits for EMI/noise protection which will feed the AC source (so I will have two layers of protection). In order to check if your line is clean firstly take some readings on the major rails (+12V, 5V and 3.3V) with the PSU in standby. If you see increased ripple (normally it should be close to zero mV) then your scope picks up noise or the PSU isn't properly isolated from the rest devices on your home/lab.
    Reply
  • CTurbo
    It's not a bad unit, but it's not competitive at all. It's more expensive than an EVGA G2 1300w Gold and and Rosewill Capstone 1200w Gold, and almost as much as an EVGA P2 1200w. Yikes!
    Reply
  • Mac266
    Shame it performed badly, a cheap high rated supply could stir the market up nicely!

    It's not a bad unit, but it's not competitive at all. It's more expensive than an EVGA G2 1300w Gold and and Rosewill Capstone 1200w Gold, and almost as much as an EVGA P2 1200w. Yikes!

    CTurbo! How ya been mate?
    Reply