120mm fan vs 80mm fan??? Power supply problem

[Artas]

Hi, everyone. I have a little problem. I'm planning to buy a new power supply, and I'm not sure which is better: 120mm fan or 80mm fan?? I read somewhere that 120 fans may be quieter;however, "problems occur with this design when the load exceeds 50%-60%. Because the 120mm fan consumes about 1.5” of vertical space inside the PSU, heat sinks, capacitors, and other components are about 30% smaller in height compared to a PSU with a rear-mounted fan. The smaller parts can handle less current, so the maximum power available with the 120mm design is limited. And, because the heat sinks have less surface area, more air flow is needed with this design to keep the thermal situation under control. With 80%-100% load, the 120’s fan speed can double and the noise level can jump by up to 20dB."
I also read that dual 80mm fans are bull.... "A power supply with two fans doesn’t exhaust any more air from the case than a power supply with one. That's because due to space limitations, only one fan can be used for exhaust, while the other is limited to spot cooling."

And finaly, I read that "MULTIPLE 12-VOLT RAILS arn't BETTER THAN A SINGLE 12-VOLT RAIL.Here are the facts: A large, single 12-volt rail (without a 240VA limit) can transfer 100% of the 12-volt output from the PSU to the computer, while a multi-rail 12-volt design has distribution losses of up to 30% of the power supply’s rating. Those losses occur because power literally gets “trapped” on under-utilized rails. For example, if the 12-volt rail that powers the CPU is rated for 17 amps and the CPU only uses 7A, the remaining 10A is unusable, since it is isolated from the rest of the system.
Since the maximum current from any one 12-volt rail of a multiple-rail PSU is limited to 20 amps (240VA / 12 volts = 20 amps), PCs with high-performance components that draw over 20 amps from the same rail are subject to over-current shutdowns. With power requirements for multiple processors and graphics cards continuing to grow, the multiple-rail design, with its 240VA limit per rail, is basically obsolete.
PC Power and Cooling is once again leading the industry. All of our power supplies now feature a large, single 12-volt rail. The design is favored by major processor and graphics companies, complies with EPS12V specs (the 240VA limit is not a requirement) and is approved by all major safety agencies such as UL and TUV."

All this information is from this site:
http://www.pcpower.com/technology/myths/

Can anyone veryfy this? Because,know, I'm really confused...I don't know what to buy... Thank You!!!!

p.s. HELP!!! ;)

[rond36]

Hello Artas, and welcome to The PC Guide Forums!

You may want to read through this thread
http://www.pcguide.com/vb/showthread.php?t=53000

I ended up buying the Silverstone Olympia OP1000 with a single 80 amp +12V rail and an 80mm fan mounted in the rear of the unit.

Depending on your system specs you may not need a PSU like the OP1000, PC P&C Turbo-Cool 1KW, or Silencer 750.

This thread would get more attention in the Buying and Upgrading Advice forum.

[jlreich]

If you are willing to dish out for a PC Power & Cooling or Silverstone PSU then a large single +12v rail is best. But if you are mere mortals like most of us and are going to stay around the $100 mark or so for an Antec, Thermaltake or similar quality brand, multiple +12v rails are best.

You can't expect a PSU in the $100 range to be able to perform like a $300+ PC P&C PSU. It's much cheaper to make a stable multiple +12v rail PSU than one with a single 80a +12v rail. It's about stability and you can't expect Antec and others to make a quality reliable $100 PSU with 1 large rail like that.

If you need and can afford a PC P&C or Silverstone, then go for it. If you have a normal system like most of us stick with multiple +12v rail PSU's. Or if you have the budget and want to feel good about it go for the big guns.

If you look at rond's thread you will see his system is not a normal system. He made a good choice with the Silverstone for his system and has the budget to back it up. ;)

[Artas]

Thanks guys!!! So it's true.... even though my computer doesn't need a power supply as powerful as the PCP Silencer 750, I'm still going for it ;)
I'm planning to upgrade my video card to a 8800gts, so i just want to be sure it will go smoothly. The other reason is because I have a mini Hi-fi connected to my computer, and with my present power supply (Bestec 300W, 12v-22A)
it kept on turning of. My pc also is noisy and crashes often, I assume that this is all because of my weak PSU. Anyway, I can't wait to get a silencer... ;)) Thanks....

[jlreich]

If your running a modern system, and I assume you are since you are getting an 8800, a 300W PSU is no doubt causing the shutdowns.

I'm planning to upgrade my video card to a 8800gts, so i just want to be sure it will go smoothly.
Actually I was just reading in PC Mag today that the 8800 uses about 50W less power than its predecessors! :cool: It's just more efficient. Much like the Core2 is more efficient than Pentium's but gets more done.