Fanless PSU + P180, a perfect pairing?

hapveg · Post by **hapveg** » Sun Apr 30, 2006 7:46 am

I understand fanless PSU's don't exhaust hot air from the case, and I've read the "Problems of Fanless PSU's", but most of that information is 2 years old, before the P180.

My questions are:

In a P180 case, is there any reason to not use a fanless PSU?

-and-

Many semi-fanless PSU's have a 120mm fan at the top, I assume these suck the air from above and exhaust at the rear? Would a P180 be better with a PSU which has the main air intake at the front of the PSU, rather than the top, since the 120mm fan in the lower compartment of a P180 would blow directly onto the front of the PSU.

IsaacKuo · Post by **IsaacKuo** » Sun Apr 30, 2006 8:23 am

The problem with putting a fanless PSU in the P180 is that the PSU is completely outside of the main airflow chamber. As such, your choices are:

1. Put a fan in the lower chamber, making the fanless PSU pointless. What's the point of getting a fanless PSU only to dedicate a fan specifically for the PSU?

or

2. Don't put a fan in the lower chamber, and hope that the PSU doesn't cook itself.

In a traditional case, a fanless PSU can benefit from airflow due to other case fans. That's not true with the P180.

The P180 is a much better fit with a quality low noise fanned PSU, ideally a straight-thru 80mm fan type.

hapveg · Post by **hapveg** » Sun Apr 30, 2006 9:30 am

Thanks for your input.

Sorry, it would have made more sense if I posted my planned system.

AMD 64 X2 3.8GHz, with Scythe Ninja (passive)
ATI 1900XT-X with Arctic Cooling Accelero X2 (0.4 Sone)
Nexus 120mm fans at 5V, probably 4.
4 x Spinpoint 160GB SATA (silent AAM), with SilentMaxx HDD Enclosures.

I'm guessing that since I'm already going to be having some Nexus fans in the main upper case, having one in the lower case wouldn't make much of a difference.

I'm thinking that almost any other fan would be more detectable than adding a 4th Nexus (operating on different frequencies or whatever), so I'm quite interested in passive PSU's. The idea borrows heavily from MikeC's tests (basically at 1M multiple Nexus fans at 5V won't really be louder than a single fan).

I've had a good look for semi-fanless PSU's using a straight through 80mm fan, but the nearest 'silent' ones I've found never go passive at any temperature.

IsaacKuo · Post by **IsaacKuo** » Sun Apr 30, 2006 9:46 am

hapveg wrote:I'm guessing that since I'm already going to be having some Nexus fans in the main upper case, having one in the lower case wouldn't make much of a difference.

Sure...and that fan might as well be the PSU fan.

I'm thinking that almost any other fan would be more detectable than adding a 4th Nexus (operating on different frequencies or whatever), so I'm quite interested in passive PSU's.

You can do a fan swap to replace a PSU's fan with the Nexus, or you can remove the fan from an efficient fanned PSU and rely upon the lower chamber fan to provide airflow through the PSU.

Of course, some fanless PSU's are very efficient. If it were my system and I was set on your strategy, I'd go with a Fortron fanless. It's very efficient and its design will let plenty of air through--taking full advantage of the 120mm lower chamber fan.

I've had a good look for semi-fanless PSU's using a straight through 80mm fan, but the nearest 'silent' ones I've found never go passive at any temperature.

A semi-fanless is not a good idea in any case. Since the PSU is outside of any airflow path, what'll probably happen is that the fan will turn on/off periodically, which is very noticeable noise.

Alternatively, if you have a lower chamber case fan, then a semi-fanless PSU fan shouldn't engage at all in the first place. Removing it would make airflow less restrictive.

hapveg · Post by **hapveg** » Sun Apr 30, 2006 10:36 am

Thank you again for your quick reply.

IsaacKuo wrote:
hapveg wrote:I'm guessing that since I'm already going to be having some Nexus fans in the main upper case, having one in the lower case wouldn't make much of a difference.
Sure...and that fan might as well be the PSU fan.

I'm hoping that using only the same brand of fans at the same voltages would give less perceived noise than using different brands. Also the PSU is at the edge of the case, while the Nexus will be in the center, hopefully reducing noise again.

You can do a fan swap to replace a PSU's fan with the Nexus

That seems like a good idea, I've never done a fan swap before, but it seems straight forward.

I'd go with a Fortron fanless

The Fortran is only 300W, using the PSU calculator it looks like I'll need about 543W, I'd rather use a completely fanless PSU (I already have a Yesico 350W), but they only supply smaller wattages, hence the semi-fanless. I'm hoping if it is adequately cooled by the Nexus fan the PSU fan will stay inactive.

or you can remove the fan from an efficient fanned PSU and rely upon the lower chamber fan to provide airflow through the PSU.

I am considering a Nesteq 620W, it's main air intake is a top fan, but if I cut the front panel off it will allow the Nexus to blow straight through.

I'd feel more comfortable removing the PSU fan completely if I had a way to measure temperature of the PSU through BIOS / software, is that possible?

Shobai · Post by **Shobai** » Sun Apr 30, 2006 1:59 pm

just FYI, it's an X2 3800+, as opposed to a 3.8GHz chip. probably justa typo, but you don't want to get mugged/jumped on by the purists..

TomZ · Post by **TomZ** » Sun Apr 30, 2006 5:43 pm

hapveg wrote:it looks like I'll need about 543W, I'd rather use a completely fanless PSU (I already have a Yesico 350W)

Many of those power calculators overestimate the power requirements, as you may have heard. I can't see how your system could possibly consume nearly that much power.

Bar81 · Post by **Bar81** » Mon May 01, 2006 3:49 am

The idea you expressed originally is the superior choice. First off, no PSU fan is as quiet as a 5V Nexus 120mm. Second, the Nexus 120mm is in the center of the lower chamber as opposed to near the exterior of the case in the case of a PSU fan so any noise is even more muffled. To boot, your Silverstone with a Nexus 120mm is now what amounts to a 400W+ PSU. Finally, no need to do a fanswap and void your warranty.

BTW, with regards to power, note that my system is running at 2.55Ghz, dual core, with RAM at 255mhz, and X1800 XL at XT speeds fully prime and 3D stable. Those calculators are shit, always will be because they have to account for the crap PSUs that make up the majority of the market that don't even come close to their rated wattage.

Ackelind · Post by **Ackelind** » Mon May 01, 2006 11:37 am

P180 + Phantom 350W fit together like hand and glove.

Cooling is provided by a 120mm nexus fan, which besides being quieter than a Seasonic S12 (yep, I've tried 'em both) also cools hard drives much better. The only downsides is that it is a PITA to fit everything, and hiding cables is a bit harder (with a fan-cooled PSU, you can stick the cables on the opposite side of where the PSU fan is located, with a fanless PSU, you want as much space around the PSU as possible).

hapveg · Post by **hapveg** » Mon May 01, 2006 11:56 am

A fanless 350W PSU may work well with a P180, but probably not in my case.

The 534W may be an overestimation, but I doubt a 350W PSU would power my planned components.

My current (fanless) Yesico 350W PSU occasionally has problems with my current PC, while my 400W Zalman works fine.

Current PC is:
AMD Sempron 3400+
1 GB RAM (noname)
3xSATA Spinpoint 160GB
nvidia 6500 (passive)

The specs for the new PC are here

Maybe a 620W PSU is overkill, but I'd be suprised if even a high quality 350W would work. Do 350W PSU's even have the PCIe connectors used by power hunger video cards?

Edit:
rereading the previous posts I may be wrong. Maybe my Yesico 350W PSU is just getting old or faulty, or maybe it's just one of the crappy PSU's which don't reach their rated wattage. Still, I'd be very pleasantly suprised if I could run my new system on a truely fanless PSU.

Bar81 · Post by **Bar81** » Tue May 02, 2006 3:38 am

hapveg wrote:A fanless 350W PSU may work well with a P180, but probably not in my case.

The 534W may be an overestimation, but I doubt a 350W PSU would power my planned components.

My current (fanless) Yesico 350W PSU occasionally has problems with my current PC, while my 400W Zalman works fine.

Current PC is:
AMD Sempron 3400+
1 GB RAM (noname)
3xSATA Spinpoint 160GB
nvidia 6500 (passive)

The specs for the new PC are here

Maybe a 620W PSU is overkill, but I'd be suprised if even a high quality 350W would work. Do 350W PSU's even have the PCIe connectors used by power hunger video cards?

Edit:
rereading the previous posts I may be wrong. Maybe my Yesico 350W PSU is just getting old or faulty, or maybe it's just one of the crappy PSU's which don't reach their rated wattage. Still, I'd be very pleasantly suprised if I could run my new system on a truely fanless PSU.

What are you talking about? That system is, sorry to say, pathetic in terms of power. The Silverstone fanless will run that without a sweat.

jaganath · Post by **jaganath** » Tue May 02, 2006 4:04 am

That system is, sorry to say, pathetic in terms of power.

Or alternatively, you could say it was very energy-efficient.

Two different ways of looking at the same system.

My power calc for your new rig:

X2 3800: 89W max (probably much less during normal use)
ATI X1900XTX : some sources say 175W max. I find that hard to believe. There are other cards with similar performance which use less power.
4 SATA Spinpoint: 40W idle, 60W on spin-up.
Nexus fans (4): 12W max.
RAM: 5W
Motherboard: 15W?

So a less power-hungry graphics card would bring your setup comfortably into sub-300W territory.

Bar81 · Post by **Bar81** » Tue May 02, 2006 4:55 am

jaganath wrote:
That system is, sorry to say, pathetic in terms of power.
Or alternatively, you could say it was very energy-efficient. Two different ways of looking at the same system.

My power calc for your new rig:

X2 3800: 89W max (probably much less during normal use)
ATI X1900XTX : some sources say 175W max. I find that hard to believe. There are other cards with similar performance which use less power.
4 SATA Spinpoint: 40W idle, 60W on spin-up.
Nexus fans (4): 12W max.
RAM: 5W
Motherboard: 15W?

So a less power-hungry graphics card would bring your setup comfortably into sub-300W territory.

lol, need to work on my people skills

It would have to be fanned to handle that., but the silverstone shouldn't break a sweat with a nexus 5v in the bottom chamber.

My system for comparison has 3 HDs with one being a Raptor obviously as well as 4x120mm Nexus at 5V and your vid card probably pull less power than mine as mine's oc'd to XT speeds.

The most important thing to do is rip out the VGA duct in it's entirety and forget about the acoustipack - it's going to turn your system into a furnace. Not to mention that sealing off all your HDs is a bad move as well temp wise; I doubt they'll be audible outside of seek in the P180 grommet setup.

The Arctic Cooling unit for your vid card isn't going to be nearly as quiet as a Zalman VF-900 so dump that too. And don't use the top fan duct; seal it off with some HVAC tape; it's useless.

CPU you would be better off with an Opteron. In my experience they run off lower voltage and are superior CPUs to the X2s if you want to OC.

Watercooling is out of the issue for more than the CPU; the reserator simply can't handle that vid card and anything fanned would kill the quiet aspect of the system.

Finally, the mobo. Are you looking for anything specific in terms of features?

hapveg · Post by **hapveg** » Tue May 02, 2006 5:19 am

Sorry, posting my *current* system specs has made this thread as clear as mud.

Jaganath calculates that at peak I'd need 356W (sorry, I'd like to stick with the power hungry X1900XTX), so if I got a 400W+ PSU I should be OK?

Silverstone PSUs, the only ones rated at 400W+ have a minimum of 22dBA fans

If all I need is a 400W+ fanless / semi-fanless PSU with a PCIe connector the cheapest I can find is the 450W Nesteq Semi-Fanless. It looks good on paper, but since they haven't sent a sample to SPCR for review I'd be a bit unsure.

Thanks for the tips on the Zalman VF-900, ripping out the VGA duct and taping up the top fan duct.

Watercooling = not useful, thanks, it's good to know I can stop pondering that.

Opteron... Interesting, I've very rarely heard them mentioned in gaming forums / benchmarks. I'll have to read up on them.

Mobo, I'm still clueless, all I want is a fanless on, preferably high spec, able to work with fast memory, but the high spec ones seem geared to SLI / Crossfire. Would there be any problems using an nForce chipset with an ATI card, they haven't included any 'optimisations' designed to cripple the competition?

Edit: reading my main system thread, I'm considering waiting till the end of the month to got an AM2 CPU / Mobo / DDR2 RAM, and 'just' upgrading the case / psu / vidcard / etc. in the next few days.

Shadowknight · Post by **Shadowknight** » Tue May 02, 2006 6:57 am

Bar81 wrote: forget about the acoustipack - it's going to turn your system into a furnace. Not to mention that sealing off all your HDs is a bad move as well temp wise; I doubt they'll be audible outside of seek in the P180 grommet setup.

Er, no. Plenty of people have used acoustipack on these forums without temps increasing. I have two systems myself with acoustipack, and temps didn't change at all.

Bar81 · Post by **Bar81** » Tue May 02, 2006 7:08 am

Remember, your setup is very similar to mine except mine draws *more* power than your system and it runs fine with a Silverstone 300W fanless (with the Nexus 120mm at 5v). Remember that the silverstone is actually a 400W+ fanned PSU that has had the fan removed and huge heatsinks placed inside and a ridged exterior. It has a ridiculous power reservoir; it's over engineered in every way. It's just a gorgeous piece of kit and to top it all off, no humming or other noise - silent perfection. The best PSU I have ever tried and I've had them all (PC P&C, Antec, SilenX, Zalman, etc)

fyi, the Silverstone also comes with a 6pin PCI-E connector for vid cards.

As to the Opteron, it's the same as the X2 except it's been put through an extremely rigorous testing process as it's designed for server use (still socket 939 though and they always come with 1MB L2 cache which is good for about a 5% performance bump from the 512k cache cpus). That means that the Opterons generally operate at higher speeds at lower temperatures than X2s and have a better memory controller than X2s for those memory overclocks with 2GBs of RAM (yes, there is a difference, it's quite hard to drive 2GBs of RAM to higher speeds). I've used both a X2 4400+ and the Opteron 170 I have now and the opteron is a better chip hands down in every way.

Yes, most of the higher end mobos that you see are over featured and cost an arm and a leg. If you go S939, check out the ASRock board I have. It does everything you could want and overclocks well but has limited voltage options (which is why the Opteron is perfect for it but not the X2 which needs more voltage to overclock). It gives 2.7v on the RAM which is enough for 250mhz+ (I'm currently at 255mhz but I've been travelling so haven't had a chance to try any higher). Alternatively in the S939 arena, I hear good things about the Sapphire PURE mobo (certainly looks the part) as it's designed well and the BIOS is finally at the point that the bugs have been ironed out.

Probably a good idea to wait for AM2 later this month but frankly, if I were you I would wait for July and Intel's Conroe and then decide.

Bar81 · Post by **Bar81** » Tue May 02, 2006 7:09 am

Shadowknight wrote:
Er, no. Plenty of people have used acoustipack on these forums without temps increasing. I have two systems myself with acoustipack, and temps didn't change at all.

errr, if you say so. I'm not quite sure how everything else being equal, adding thick insulation doesn't alter temps. In my experience (and apparently those of home builders

) it certainly does.

Shadowknight · Post by **Shadowknight** » Tue May 02, 2006 7:17 am

Computer cooling is based on airflow. Other than the hard drive, no other heat producing device touches the case, thus no heat from those devices are cooled by the case itself. If you depend on your case metal for cooling, trust me, you're already screwed.

Bar81 · Post by **Bar81** » Tue May 02, 2006 8:14 am

That's not relevant. The insulation absorbs heat and traps it. By your example, unless people and the TV and the dryer are stuck to the outer wall of a house then the insulation should have no effect.

Shadowknight · Post by **Shadowknight** » Tue May 02, 2006 8:17 am

Bar81 wrote:That's not relevant. The insulation absorbs heat and traps it. By your example, unless people and the TV and the dryer are stuck to the outer wall of a house then the insulation should have no effect.

One time my exhaust fan stopped moving. The case was burning to the touch without any airflow. Everything shut down due to thermal throtelling. Cooling IN A COMPUTER is based solely on airflow. You have a very small environment (case) that is cooled by moving airflow. The end. The exception to this rule are purely passive cases such as the TNN line from Zalman, and certain computers from Hush.

Bar81 · Post by **Bar81** » Tue May 02, 2006 8:25 am

Thanks for telling me the end and all but I'll go with what I know and what happens in the real world over your proclamations. It's insulation, it's purpose is to absorb and retain heat and it does so. For our purposes it is usefull due to its sound muffling properties but that doesn't somehow cancel out the fact that it is insulation.

Of course, if you're increasing the airflow in your case to compensate for the insulation then that's another story but if you're running a low airflow quiet system then insulating the case will make a difference temp wise. THE END

IsaacKuo · Post by **IsaacKuo** » Tue May 02, 2006 8:30 am

This reminds me of people who insist that aluminum cases run cooler than steel cases...

Bar81 · Post by **Bar81** » Tue May 02, 2006 8:32 am

IsaacKuo wrote:This reminds me of people who insist that aluminum cases run cooler than steel cases...

This post reminds me of a useless post... oh, wait

Shadowknight · Post by **Shadowknight** » Tue May 02, 2006 9:22 am

Bar81 wrote:Thanks for telling me the end and all but I'll go with what I know and what happens in the real world over your proclamations. It's insulation, it's purpose is to absorb and retain heat and it does so. For our purposes it is usefull due to its sound muffling properties but that doesn't somehow cancel out the fact that it is insulation.

Of course, if you're increasing the airflow in your case to compensate for the insulation then that's another story but if you're running a low airflow quiet system then insulating the case will make a difference temp wise. THE END

... I've stated that I have two systems with Acoustipack applied. Both of them have Nexus fans running at 650rpm or lower. I HAVEN'T increased fan speeds, and temps have remained the same. What more real world experience can I provide? Other people on the forum have had zero impact on temps from doing the same thing.

Putting insulation in a computer IS NOT THE SAME AS PUTTING IT IN A HOUSE.

I give up.

jaganath · Post by **jaganath** » Tue May 02, 2006 10:14 am

Putting insulation in a computer IS NOT THE SAME AS PUTTING IT IN A HOUSE.

Actually the two applications are semi-analogous, however I suspect 99.9% of the heat energy leaving a computer case does so via more energetic air molecules which are expelled by axial impellers (forced convective flow), whereas with houses ISTR that much more heat is lost by conduction through the walls etc; this is why terraced houses tend to need less heating than detached, as only 2 sides are exposed to cold ambient air versus all sides for a detached house. Still, badly insulated houses lose a lot of their heat via hot air escaping from the roof (ie normal convection).

My main points is (I know it's not clear) in a computer case very little of the heat produced by the components reaches the exterior by conduction through the case walls; heat is transported so quickly out of the case by forced convection that it doesn't have enough contact time with the case walls to warm them up significantly, which is why acoustic insulation doesn't tend to have a negative effect on temps.

florecilla · Post by **florecilla** » Fri May 05, 2006 6:38 am

IsaacKuo wrote:

> The problem with putting a fanless PSU in the P180 is that the PSU is completely
> outside of the main airflow chamber. As such, your choices are:
>
> 1. Put a fan in the lower chamber, making the fanless PSU pointless. What's the point of
> getting a fanless PSU only to dedicate a fan specifically for the PSU?
> .......

Hi Isaac. Looks to me (anyway, I don't have a P180 so I can't know) there is an advantage to this. The user mounts a fan outside the PSU, reducing turbulence, cavitation noise, airflow deadspots and direct sound escape paths. In theory, if he uses a thick, big, quiet, undervolted fan with no obstructions in one or two inches from it, that should help. Besides, 120 mm fanned PSU's force air to make a 90Âº turn wich is suboptimal, while a straight through PSU requires 80mm fans (always more noise per CFM)

The disadvantages I see are:

1) a user claimed the lower chamber of the P180 resonated at the fans frequency
2) some fanless PSU's like the phantom are too large and don't leave much room at all for the fan. The more free room around the fan, the less obstruction, the better.

What's your opinion on this?

Post by **MikeC** » Fri May 05, 2006 8:06 am

florecilla wrote: Hi Isaac. Looks to me (anyway, I don't have a P180 so I can't know) there is an advantage to this. The user mounts a fan outside the PSU, reducing turbulence, cavitation noise, airflow deadspots and direct sound escape paths. In theory, if he uses a thick, big, quiet, undervolted fan with no obstructions in one or two inches from it, that should help. Besides, 120 mm fanned PSU's force air to make a 90Âº turn wich is suboptimal, while a straight through PSU requires 80mm fans (always more noise per CFM)

The disadvantages I see are:

1) a user claimed the lower chamber of the P180 resonated at the fans frequency
2) some fanless PSU's like the phantom are too large and don't leave much room at all for the fan. The more free room around the fan, the less obstruction, the better.

What's your opinion on this?

Much of your comments about turbulence, cavitation noise, etc, are valid.

Truth be known, almost any PSU can be run in the P180 w/o a fan in the PSU. You do need a 120mm fan in the chamber, run at slow speed (5~7V) for >10cfm (there are a bunch of quiet ones you can choose from). Simply remove the PSU's internal fan before you install it in the P180. Make sure the fan in the middle of the lower chamber is on all the time. If it looks like there is too much impedance in the airflow path through the PSU, cut out any restrictive grills and close up the extra vent openings around the PSU on the back panel of the case. This will ensure that the air from the fan is forced through the PSU rather than around it.

jaganath · Post by **jaganath** » Fri May 05, 2006 10:09 am

Much of your comments about turbulence, cavitation noise, etc, are valid.

I may be mistaken, but I'm not sure cavitation is an issue with axial PC fans. AIUI, cavitation refers to the formation of vaporous bubbles in a liquid when the local pressure falls below the vapour pressure of the liquid at ambient temperature (ie the boiling point of the liquid falls below ambient temp); this can't happen in air, because air is already in a gaseous state, there is no "higher" phase state (apart from plasma, obviously, but that is not relevant in this specific case).

Post by **MikeC** » Fri May 05, 2006 10:16 am

jaganath wrote:... I'm not sure cavitation is an issue with axial PC fans. AIUI, cavitation refers to the formation of vaporous bubbles in a liquid when the local pressure falls below the vapour pressure of the liquid at ambient temperature (ie the boiling point of the liquid falls below ambient temp); this can't happen in air, because air is already in a gaseous state, there is no "higher" phase state (apart from plasma, obviously, but that would take ambient temps of thousands of kelvin).

uh... terminology overload... ok, it's cavity air resonance I was thinking of, tho it's true that just having a fan in the lower chamber is probably enough to excite the chamber's air resonance anyway. With a low speed, low vibration fan, it's usually not much of a factor.

cmthomson · Post by **cmthomson** » Fri May 05, 2006 1:20 pm

MikeC wrote:ok, it's cavity air resonance I was thinking of, tho it's true that just having a fan in the lower chamber is probably enough to excite the chamber's air resonance anyway. With a low speed, low vibration fan, it's usually not much of a factor.

Depends on the fan. I got cavity resonance with an AcoustiFan at 5V in the lower chamber of the P180. A Nexus did not resonate at either 7V or 5V.