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apav

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  1. Informative
    apav reacted to bowrilla in Case pressure questions, does airflow scale linearly with fan speeds and what effect does a radiator have on pressure?   
    One of the biggest factors though is the gap between frame and blades. This area increases obviously even it is was the same 2mm gap. The blade geometry can be scaled and since angular velocity is the same for all parts of the blades it means that the blades will cover the gaps inbetween the blades in the same time interval (therfore the outer blade tips of a 140mm fan will be quicker than the ones of a 120mm fan at the same rpm). You will usually see 2 things on high static pressure fans: 1st smaller gap between blades and frame 2nd larger fan blades. The latter however is a matter of how you design them. Take the Arctic P14 for example: optimized for higher static pressure with a blade geometry you'd expect on a high airflow fan. It works though and those are among the best. In order to have high static pressure at low revs you'd want longer and more angled blades to cover more surface at any given time interval. The higher the rpm though, the shorter the smaller this surface area becomes at the same time interval.
     
    That's a big maybe. It depends on the manufacturer and the model. Let's take some quick measurements. I quickly measured all the fan hub diametres I had with a caliper:
    Fractal Design Silent Series R2 (92mm): 34.9mm
    Scythe SU1225FD12M (120mm): 42.3mm
    BeQuiet! Silent Wings 3 (120mm): 42.9mm
    Cooler Master MasterFan 120AB (120mm): 42.1mm
    Noctua NF-A14 Industrial PC (140mm): 42.2mm
    BeQuiet! Silent Wings 3 (140mm): 50.3mm
    Arctic P14 (140mm): 42.1mm
    Phanteks PH-F200SP (200mm): 52.9mm
     
    That's all the fans I have available that are not tucked into a system. As you can see: the measurements can vary but it's not a must. The BeQuiet! SilentWings 3 fan is the only 140mm fan that is actually significantly larger in regards to hub diametre and almost as large as the Phanteks 200mm case fan. 
    Well, I agree that static pressure is important especially at lower RPMs but the thing is: you can always just up the revs to compensate. It's similar (but not the same) to torque and power on a car: it is tightly related (torque * angular_velocity = power). The static pressure gives you a figure of how much restriction you could overcome, the actual restrictiveness along with the static pressure at X rpm gives you (roughly) your effective air volume. At the end of the day, both static pressure optimized fans and airflow optimized fans do the same thing: they move air. The static pressure optimized fan is similar to a diesel: lots of torque (static pressure) at lower rpm. The airflow optimized fan is a petrol engine: more power (airflow) at higher rpm with less torque (static pressure). Again: don't take the analogy literally. So a fan with less static pressure will need to have higher rpm to move the same amount of air volume through a specific restrictiveness Z.
    That however is a poor way to reduce restrictiveness. A better way would be to lower the fpi (fins per inch). More or less fins does not necessarily mean more water channels (and if you've ever had a look inside a radiator, you'd see that those channels are really small). Of course, going for a thicker radiator will increase the volume both at the end tanks as well as the volume of the channels. Yes, they also increase restrictiveness. That's why thicker radiators often benefit from Push-Pull configurations while 30-35mm radiators don't. Thicker radiators scale a lot more with fan rpm than slimmer radiators as well. A good slim radiator however beats or at least equals most thick radiators at low to mid rpm. It's only at the top end, that thicker radiators will offer more performance. But if that was important, you could just go for crazy high fan speeds as well and give a f about noise.
     
    Obviously. But the material is a given with custom open loop water cooling (copper for the radiator and blocks, maybe nickel plated but the base is still copper; Alu is a niche material here). The contact area size indeed is important (this is where thicker radiators shine but their increased restrictiveness leads to higher rpm in order to use that area). With a given surface area for the heat exchange and obviously a constant material, the most important thing is the ΔT. You can shove 100000cfm through your radiator but if the ΔT is only 0.0001K you won't have much heat transfer going. The bigger the gradient the more heat you can transfer between medium A and medium B. 
     
    Of course. The Die is very small and neats to transfer heat to the IHS. Surfaces are not groved so contact area is basically flat, the thermal compound only fills the gaps but still is a poor conductor (hence the benefits from soldered IHS). Now we put our block on top of the IHS and we again need to fill gaps with thermal compound. Throw away the IHS and you already increased cooling performance because there's one less heat transfer going on.
     
    Yes, I have my doubts though that we'd ever see this in mass market applications. 
  2. Informative
    apav reacted to Bombastinator in Case pressure questions, does airflow scale linearly with fan speeds and what effect does a radiator have on pressure?   
    I do not disagree with your assessment, but I thought It could be useful to give you my understanding of this.  I looked into this stuff quite hard once upon a time but it was long ago.  Might be useful, might not.
     
    My understanding is what makes 140mm fans have lower static pressure in general than 120mm fans is the fact that the hole is bigger and hence the spaces between the blades are bigger.  Blade design matters though.  It would not at all surprise me if a high static pressure 140 might have higher static pressure than a low static pressure 120.  If the blade shapes are identical though the 140 will have higher cfm but lower static pressure.  This is complicated by fan thickness being limited to 25mm regardless of size.  A 120mm fan is effectively relatively a bit thicker than a 140mm fan ratio wise.  It will also have effectively a slightly larger hub.  Fans in computer cases have been getting bigger because when static pressure is low enough, a 140mm fan can be more efficient than a 120mm.  200mm even moreso. This is partially offset by the static pressure issue because a higher static pressure fan can blow through more narrowly spaced fins.  Look at the fin spacing of an air cooler designed for a 92mm fan compared to the fin spacing of a cooler  designed for 120mm.  The 120mm cooler will have wider spaced fins. There were some really bad cases sold some years ago because cases designed for 120mm fans simply had 140mm fans stuffed in then.  Sometimes this worked if the necessary static pressure was low enough, and the result was a quieter case.  when it wasn’t it worked very very poorly, and the result was a hot case.  Hub size does matter a bit and that can get very pronounced with very small fans (40mm)  but the difference between 120mm and 140mm isn’t all that pronounced.  The deal with radiators though is static pressure is what is needed to push air through resistance, such as around a corner or through a slot or a radiator.  If the static pressure is too low it doesn’t matter if the cfm  is higher because no more air will flow through the radiator than the static pressure allows.  Extra air simply won’t go through the radiator.   This is easy to solve by lowering the resistance of the radiator which is generally done by making such radiators thinner.  It’s not the only way but it is a common one.   A thicker radiator will be higher resistance.  Also a “tighter” radiator. Both will also have more water in them.  
    deltaT does matter, but it’s not the only factor.  Material type matters too as well as contact area size.  The contact area size is apparently part of the IHS problem.  Chips have gotten smaller and smaller over the years and they’re still made of the same material.   There have been moves to alter this.  I read about one recently out of Switzerland that apparently cut grooves in the silicon to effectively increase its surface area while using a flowing liquid system to increase under IHS heat transfer. 
  3. Informative
    apav reacted to bowrilla in Case pressure questions, does airflow scale linearly with fan speeds and what effect does a radiator have on pressure?   
    Depends on the model. Static pressure is important but at the end of the day, it's the air volume that is responsible for the heat transfer. You'd need to push the specific numbers here. There's also the dead spots underneath the hubs and around the frames where almost no airflow happens in some situations. I'd need to think about wether a larger fan with a larger surface but the same restrictive radiator properties would need more, the same or less static pressure to push the same air volume. My intuition says less static pressure but I'd probably need to go into some formulas to find that out.
    The surface and water content of a 360 radiator is only marginally larger (~5.5%) compared to a 280 radiator while you will have 3 noise sources vs 2, and you'd have 3 dead spots and not just one.
     
    The problem in general is heat transfer. Heat transfer depends on the heat gradient ΔT between the two media. In any even remotely decent loop the gradient between CPU/GPU and the coolant will always be greater than the gradient between the coolant and the ambient air. Therefore a slightly hotter coolant temperature is of greater benefit. Let's say you'd aim for 35°C coolant temp and let's assume a maximum temp of the CPU during a stress test of 60°C (it's a realistic example, should be pretty reasonable unless you try to really push it in my opinion, but you can switch the figures to your liking) and a room temp of 20°C. That means you'd have a gradient of 15K between ambient air and the coolant but a gradient of 25K between the coolant and the CPU. Dropping the coolant temp by 2K will decrease the ambient air/coolant gradient by ~13.3% while you'd increase coolant/CPU gradient by 8%.
     
    Long story short: don't fuss too much about extra cool coolant temps. At the end of the day, your CPU doesn't care about 2, 3 or 4K higher temps as long as it stays reasonable. That leaves more room to dial down noise levels.
    Fully agree.
     
    It does not unfortunately. You'd need to measure every single model because it all depends on blade geometry. And don't even bother getting absolute figures. Your only hope is to stick to a certain measuring rig.
     
    As said by @Bombastinator it depends on the specific fan, the specific radiator, the specific case and the position at which you'd be mounting it, additionally the aerodynamics of the system's internals ... I think you get the point? All you can hope to get as an answer is: the mroe you put directly into the airflow, the more you restrict it. By how much is beyond anyone's scope on this forum to tell you - and beyond manufacturer's to tell you because they can't test every single configuration.
     
    Test it out.
  4. Informative
    apav reacted to Bombastinator in Case pressure questions, does airflow scale linearly with fan speeds and what effect does a radiator have on pressure?   
    The easy test for positive vs negativ pressure is a piece of thread: does it blow in or out when the thing is set up?
     
    as for 280 vs 360 it’s 2 140mm fans vs 3 120mm fans.  Fans for 140mm fanned radiators tend to be thinner because 140s have less static pressure than 120s. A 360 has more water and more surface area so fans could spin slower and would take longer to heat up. 3 fans instead of 2 fans though so quieter at low speed if you get into that hook I was talking about, otherwise it can be noisier.  The problem with moder CPUs isn’t moving heat from the cold plate to the radiator though, it’s moving heat across the IHS.  So a  lower water temp can help some but not a lot. 
     
    It seems like you want really accurate predictions before buying stuff and trying it.  The problem is airflow is fluid dynamics which is just hard to predict without knowing all kinds of information and then often requires complex hard core computer modeling.   Engineers used to do testing for this sort of stuff with wind tunnels.  All I’ve got is “a little”, “some”, and “a lot”.  
  5. Informative
    apav reacted to Bombastinator in Case pressure questions, does airflow scale linearly with fan speeds and what effect does a radiator have on pressure?   
    none of these are I think as straight as you describe them.
     
    1: varies by fan model.  There was sometimes a graph printed on the box.  The graph tended to be a curve with a hook in the bottom I remember it was generally shallower than 45° But that may have just been the fans I was buying.

    2: varies by fan model AND radiator model, but a lot 
  6. Informative
    apav reacted to TVwazhere in Replacing stock NZXT Aer P fans on the Kraken Z63 with Noctua NF-A14 fans   
    Ah okay,
     
    The AER P fans achieve a "higher static pressure" because they spin up to 2000RPM (as opposed to only 1500) as well as not all testing is done the same so sadly you cant compare specs 1:1 (especially when it comes to noise). By any account though, the A14's at their 24dBA rating will definitely be quieter than the 38dba rating of the AER PP's at max RPM's regardless of measurement methodology. Unless you're running your fans at full RPM, you probably wont notice a significant temperature difference. 
  7. Informative
    apav reacted to TVwazhere in Replacing stock NZXT Aer P fans on the Kraken Z63 with Noctua NF-A14 fans   
    Correct. Stats pages only list maximums, which most people never hit since they don't run their fans at full speed typically. Noctua's have good performance even when not at their max RPM's. 
     
    Currently their best Radiator fan is the NF-A12x25; they're supposed to release an A14 version but it's bene in development for quite some time now. 
  8. Informative
    apav reacted to TVwazhere in Replacing stock NZXT Aer P fans on the Kraken Z63 with Noctua NF-A14 fans   
    P14's are actually the pressure optimized versions of the F14's. The P12's are not too far off from NF-a12x25 performance but for a much lower cost (a 5 pack for the dc-dc is $30) so the P14's should follow that trend of good price-performance, as well as being white for the HALO RGB grills. 
  9. Like
    apav got a reaction from konorok in Calibration Retry Count error on HDD?   
    Hey guys,
     
    Just noticed my external HDD shows up having a Calibration Retry Count error, and the Data value is 5.  According to Crystaldisk, it also reads 5 under Data, but Recalibration Retries is blue instead of yellow (meaning it's normal) and my health status is Good. I have no idea what this means, only that potentially it could be a problem. I ran an error scan but everything was fine. I also ran a short drive self test and a short genereic test in Seatools, and both tests passed. Looking the error up says it is a sign of a potential drive failure. Should I be worried? Also side question, is there a way to backup 560 GB of data on that drive into a much smaller size with a backup software? How small could I possibly get that backup (containing all 560 GB of everything on that drive) to be? I've never backed up a drive of that size before.
     
    Thank you! Oh and here's a picture in case you're wondering:
     
     
     

  10. Funny
    apav got a reaction from seduce_me in AMP / DAC for AKG K712 PRO for Gaming   
    This may be an unpopular opinion, but if you really like neutral, uncolored sound and don't mind saving up a bit more I'd jump on the CEntrance DACMini CX the next time it's on Massdrop (discounted to $400). In terms of quality, it competes against really expensive DAC/Amps at a much cheaper price. 
  11. Like
    apav got a reaction from STRMfrmXMN in Win10 is full blown electronic tyranny   
    I care about my privacy. But I don't care to the point of refusing to use Windows 10. The features and improvements are way more important to me. It's also why I use Gmail, it's very convenient and I don't feel like changing (really though I'm sure any email is bad, maybe not on Google's level though). I just disabled everything I can on Windows 10 that's known to collect data and hope nothing will happen that will directly affect me. 
     
    Besides, while I understand privacy concerns, all I have on my computer is schoolwork, games and mods, music, pictures, videos, etc. For someone like me who doesn't have THAT important or sensitive data, what's the worst that can happen? It's not like they're going to access my naked baby pictures and post them on the front of Microsoft's website. 
  12. Like
    apav got a reaction from STRMfrmXMN in Spilled Proseco on my K90, can I get it working again?   
    Probably right, but then again I only patted the liquid down so it could still be on the circuitry. I guess I'll try drenching it in alcohol, wiping it, and drying it out.
  13. Like
    apav reacted to the jolly roger in Monster performance in a silent case possible?   
    Define R5, decent airflow, dead silence, mid tower, spacious, check, check and all the checks
  14. Like
    apav reacted to theloveablemoose in Monster performance in a silent case possible?   
    Well the GTX 980 uses very little power at idle so if you get the Asus version which will trun off the fan it will be completely silent, closed loop watercoolers can have some pump noise but running them slower gets rid of this. I would think about how silent you want your PC to be before making plans as this can effect your final part list.
  15. Like
    apav reacted to theloveablemoose in Monster performance in a silent case possible?   
    I doubt Asus would take that feature away as its one of the few selling points of their cards, as for CPU cooler do you have a prefrence to water cooling as a NH-D15 is very good at cooling and is extremely quiet but may incompatible with some cases.
  16. Like
    apav reacted to KamiKatze in Monster performance in a silent case possible?   
    +1 on the Define R5
     
     
    However a PC is only as silent as the components inside.
     
    What cards will you SLI? The Asus Strix are so far leading in silence concerns.
     
    Your old hard drives will probably be the most noisy part at idle, as it is allways difficult to eliminate all the vibrations. At leasts that's currently the state with my main PC.
     
    Airflow wise i wouldn't worry. My setup (see sig) provides enough airflow to keep temps down properly. A SLI config may require one more fan or two, but as long as you choose some very silent one for the job (bequiet, noctua or noiseblocker) you'll be very happy.
     
    Lastly, it's allways a question of how you control your fans. A smart fan controller with custom fan curves - whether this fan controller is built into your motherboard or not- will allways help a lot.
     
    Edit: oh yeah, liquid coolers will most likeley lead to a pump noise at idle. don't know if that's an issue or not, i decided to never touch liquid cooling because of that concern.
  17. Like
    apav got a reaction from Speedbird in Any drawbacks to getting a bigger HDD?   
    Well I guess I don't mind paying $7460 more.
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