I've got another update for this thread.
I just bought two FSP350 PSU's from Newegg. This PSU has a fan controller on the back, but this controller is still connected to a temperature controller. You can find Mike C's review here
My PSU's are a bit different from the one Mike reviewed, though. For one, mine don't have an LED fan. It is a simple black plastic fan. Secondly, I also noticed that this PSU uses a different fan from the FSP300 and it is different from the fan in Mike C's reviewed PSU, too (5 fan vanes, as opposed to 7, as Mike's sample had and my FSP300's have all had.)
The FSP300 uses a Yate Loon D12SM
-12 fan, rated for 56 CFM & 39 dB @ 12V. This fan is failry quiet and transparent at 5V. The FSP350, however, uses a Yate Loon D12SH
-12 fan, rated for 78 CFM & 43 dB @ 12V. Logic would dictate that the FSP350 will be louder than the FSP300, if running at the same voltage. The FSP350 does, however, have a different location and mounting for its temperature control circuit, however, so if the PSU is left unmodded, I thought it may
be quieter than an unmodded FSP300, if the temperature control circuit works better than the FSP300's temp control circuit.
You can find the Yate Loon fan specs here
I opened up the FSP350 and did a little splicing. I spliced a wire into the fan leads and ran it out of the PSU, to measure fan voltage. I also hooked up a 5V bypass for the fan, so I can switch it off the onboard controller and directly into 5V, if I want to.
I took my 5V modded FSP300 and the FSP350 (modded so I could measure fan voltage) and I tested their noise level, side by side. I found a couple interesting points.
The FSP300, in stock condition, has a starting voltage of about 4.25 volts. The FSP350, in stock condition, has a starting voltage of about 3.6 volts. The FSP350's fan is faster and louder than the FSP300 and this is immediately noticable, when comparing the two PSU's running the same fan voltage. The FSP350, at 3.6 volts (its lowest voltage level) is very close, in noise level to the FSP300, modded to run at 5V. When they are both run at 5V, the FSP350 is quite noticably louder.
I wanted to see how the temp controller worked on the FSP350, so I threw it in my dual AMD system and started it up. I let the system run for quite a while (at full load, since I fold proteins) and I was dissapointed that the fan sped up to a quite loud level. It is now running at a noisy 8.36 volts with an exhaust air temp of 37.5C. [EDIT] After modding the FSP350 fan for 5V (because it was easy), the exhaust temp only raised a bit. It is now 41.8C, which is still very safe, I believe. I will later do the diode mod to drop the voltage down some more, and then post more findings. The PSU exhaust temp, of course, is only a baseline for comparison. I've found that it is generally proportional to the PSU intake air temp. With this PSU, the exhaust temp is generally about 10C higher than the intake air temp and I am striving to keep the intake temp below 40C, with an exhaust temp not exceeding 50C.[/EDIT] [EDIT 2] I've now modded the PSU fan with two diodes, running series, between the 5V line and the fan. The measure voltage is 3.55V. The PSU exhaust temperature has raised to 45.4C. To get an idea of my case airflow, you can see pictures of my case, here.
Like everyone else, around here, I strive for low noise levels. This PSU is not low noise. It can be modded for low noise, just like the FSP300, but it is a bit more difficult. This PSU fan would need to be modded for around 3.6V, to get the noise level achievable by the FSP300, modded for 5V. The 5V mod is really easy. The 3.6V mod would take a little more work. The easiest way to achieve about 3.6V, would be to tap into the 5V line, then run two IN4001 (or similar) diodes, in series, before going to the fan. This would drop voltage down to about 3.5V (the diodes drop the voltage by about .75V each). This mod wouldn't be terribly hard, but it would mean an additional step, which you wouldn't have to take, if using the FSP300. For more information about using diodes for voltage control, please see this website.
In my experience, so far, I haven't found a single system that wouldn't run rock-solid stable, with a modded FSP300. So far, I have used a 5V modded FSP300 in two AMD duallies (running dual 2GHz Athlon XP's), a 3.0C P4 system with no case airflow except the 5V FSP300, and a 3.2C P4 system with a 9800 Pro and a 120mm Evercool exhaust fan (modded for low voltage.) All these systems are high wattage systems. The P4 systems, although running the hottest and fastest CPU's and video cards, used far less power than either of the AMD duallies, as tested with a Kill-A-Watt meter. Neither of them used more than 150 watts (from the wall), if memory serves. Both AMD duallies use a little over 200 watts.
Hope this thread helps anyone interested in the FSP300 or FSP350.