My Dell Precision T3500, with Xenon processor. Came with NO case fans. It can have two 92 mm fans rear, & 92 mm fan front. I will add two GTX 1070's & 550W gold PSU. The machine will be maxed out 24/7 'Distributed Computing' only. I was leaning to Positive psi CFM. More CFM's in than out. What spread or delta CFM's btwn in & out is better? or Example: 100 cfm IN, would 90, 80, 70...10 cfms OUT be better?
Don't worry about that positive or negative pressure stuff. The main thing is air flow through the case. If that is good, your temps will be good. If you have no fans now, adding just any fan will make a huge difference. Remember, the CPU cooler need only toss the CPU's heat into that flow. One of the reasons not to worry about + or - pressure is because without specialized measuring equipment, you cannot really tell what is happening anyway. In part because the PSU fan is pulling air in from every crack and crevice and exhausting heated air out the back too. And it is highly unlikely you know the CFM specs on that fan which also depends on the speed it is currently spinning. And with most better PSUs, that speed varies depending on the heat thresholds in the PSU. So don't worry about it. Just add fans. Personally I like a fan in front pulling cool air in, and a fan in back exhausting heated air out. I also like "blowhole" or top mounted fans that exhaust heated air out. But note front fans (and possibly blowhole fans) may produce more noticeable fan noise than two fans in back. Get the largest fans your case supports. If only 92mm then you are stuck with 92mm. If you really want to get into the thermodynamics of case cooling, I recommend you move all the components into a decent case. One that offers many fan options. I like Fractal Design cases. Most support several 140mm fans for massive amounts of air movement while nearly imperceptible fan noise. In fact, on my Fractal Design case, the only way I can tell if my rear fan is spinning (without looking through the side panel window) is to put my ear by the exhaust vent and "feel" the air blowing. I cannot tell if the front fan is spinning without looking inside. And my temps typically sit below 40°C when the computer is being tasked. I think that is a mistake and you need to do some more homework. As seen through the Specs tab here the GTX1070 pulls 150W and with one GTX1070, the recommended PSU is 500W.
Going by that Dell case, you might as well open the side panel--better yet, prop it at a 40-50 degree angle with the machine's side, leaving a gap in the back of about 2 inches. Get a smallish fan to blow air from a cooler source like an open window or air conditioner and angle it toward the interior to help drive that accumulated hot air out. Just have to watch the drinks, dirt, etc. If that Dell wasn't designed for one 1070, let alone two, just your expectations of the ideal fan placement are too high. Especially considering everything's dimensions and how you intend to use this machine.
My favorite is the Gateway FX BTX case made by Intel. Nice ducting, and very quiet. Weight a ton, though.
@Bill_Bright - this calculator, http://outervision.com/power-supply-calculator with two GTX 1070's, I chose 3 fans, utilization 100% 24/7, comes up with 550W PSU. I've seen those specs several times, why I used that calculator. Two 1070's, 4 fans 1- 140mm, 3 120mm, also chosen cpu 100%, also chose Xenon cpu (not exact match calculator does not have xenon 3500 listed. I like the idea of a new case (better cooling), than what could be accomplished, with old case. Dell Precision T3500 Is that an ATX case?
So much depends on individual components and case. Big thing to consider is, what are your biggest heat sources and how can you most quickly remove that hot air they produce and avoid recirculating hot air produced around the case. Airflow should always be front to back/top. It is peak temperatures rather than idle temperatures that you want to reduce. Thermal fatigue is a major factor in CPU failures and the rate is a direct function of the number of temperate change cycles multiplied by average temperate change above idle. http://icrontic.com/article/pc_airflow_heat_cooling_guide shows evidence that one well placed fan can be better than 2 or more poorly placed fans. "A single rear exhaust fan produces the best results overall. This flushes the theory of more is better right out the door." You don't need expensive equipment, CPUs and GPUs report temperatures, they are usually the biggest heat sources so you can experiment and take measurements (full CPU/GPU load temperatures are priority to reduce).
The two 1070 are going to be doing the 24/7 work, right? In that scenario, a fan mounted on the side panel would be a consideration in addition since those 1070 have their own fans also. If that Dell didn't come with any fans, you can infer it wasn't designed to accommodate even one higher end GPU, let alone two. Those GPUs squashed in there are obstructions to air flow. In that scenario, indeed, you might as well take the side panel off. Nice vented case and cool ambient air--that's the ticket! https://www.pugetsystems.com/labs/articles/Side-Panel-Fans-Are-They-Worth-It-102/
Good Stuff! Yes 1070's full blast 24/7 A single rear exhaust fan produces the best results overall. This flushes the theory of more is better right out the door. On side panels. I have a box, i7, gtx 960 & 1060, pedal to the metal 24/7. I put a 92mm fan on the side. Fan on or off, did almost nothing or hard to tell. Speccy temps fluctuate 1 ~ 4 degrees, seems identical on or/off It may improve air flow one 1070 full length, the 2nd half length
Ahhh, you had another setup to try out. Yeah those Speccy numbers say it all, oh well, the side fan idea was something to toss in the mix. I peeked a little at Newegg, they seem to have some great deals on some nice and well-ventilated cases, and I saw one ATX, maybe there are more to choose from. Seeing as you have two GPUs, if you do get another case, maybe consider a smallish box fan or two that can gently focus (not blast) cool air like from an AC or air duct on the machines' intakes. Just can't be too dusty or wet or whatever and you'd have to check for dust/dirt buildup somewhat more often. See if that helps even more. Neat project! Hope you find a case worthy of those mighty 1070s
Calculators are notoriously unreliable, real world scenarios usually tell a different story, see the bottom of this page for a more realistic proposition. That's a full tower (too large for your needs). I'd go with the R5 and add a second intake fan (those two 1070s can produce a lot of heat) for a total of 2x140mm intake, 1x140mm exhaust. The case has an inbuilt fan controller with 3 speeds which even at max keeps things silent.
Not the eXtreme Outervision PSU calculator. It is, by far, the best one out there and the only one I trust and recommend - especially for experienced users. This is because there is a team of developers and research analysts who are constantly researching components and updating the calculator. No other calculator maintains such an extensive and inclusive database of different CPUs, graphics cards, RAM, fans, drives and more. And no other calculator lets you adjust for various utilization, number of devices, and even overclocking. The bottom of that page you linked to is NOT realistic because it is based on one specific motherboard, one specific CPU, RAM, etc. It is only realistic when comparing that card under test with other cards using that same motherboard/CPU/RAM platform. All PSU calculators tend to pad the results. It is always better to buy too big a PSU than too small. But the eXtreme calculator is the most conservative, but at the same time, allows experienced users to add their own padding based on their own anticipated usage. @Rico - you were wise to use that Calc and setting utilization to 100% and 24/7 operation adds a nice bit of head room (padding). But without knowing the rest of your hardware, I cannot verify the recommended 550W really is enough. It appears to be but without knowing which CPU, what kind and how many sticks of RAM you have, type and number of drives, etc. we cannot verify. Even if 550W is enough, it may not leave you enough headroom to upgrade your CPU, for example, should you decide to in a year or two. As to that Dell T3500 case, I am assuming you have one laying around because I don't believe you can buy just the case. I do not recommend reusing cases from factory built computers - especially from the big computer makers. This is because they often have proprietary features that make using 3rd party components a challenge, if not impossible. And Dell is known for that. I think the R5 is an excellent choice. Note it comes with 2 x 140mm fans which may be plenty considering those graphics cards exhaust heat directly out the back.
It's realistic to me because it represents a real world scenario. Besides I'm sure you'd agree with their recommendation of 650w minimum for SLI. The OP didn't specify which 1070, if it is a custom variant the hot air will mostly blow inside the case. Anyway, whichever card(s) I would always add a second front intake (the fan I linked above is exactly the same as the included ones) for 3 reasons: - the fans blow at 1000rpm max which is a bit on the conservative side - 3x140s at full are inaudible inside that case - the fan controller allows for 5v/7v/12v (aprox. 500/700/1000rpm) so you can adapt cooling to conditions
"A" as in "1" single, unique, real world scenario. That's the problem. Everybody's computer is different. Do you have that exact same CPU, RAM type and number of sticks, number and type of drives? Same number and size fans? I have 6 computers here and none have that same setup. I bet yours don't. And I am sure Rico doesn't either. With that eXtreme PSU calc, you can plug your specific CPU, your specific RAM, specific drives, etc. and get a realistic and unique recommendation for your unique real-world setup. Not Guru3D's unique setup. It is a mistake to lump all PSU calculators together. They are not all the same. You don't condemn all cops because some cops are dirty. You don't condemn all security programs because some are rogue. You don't condemn all lawyers because some are shysters. Well - lawyers might be the exception! Yes, based on what we know, I would be more comfortable with a good quality 650W. But not because I think the eXtreme calc is wrong. I prefer more headroom because I hate fan noise. And the 650W would likely be able to support the equipment without ramping up the PSU fan speed to full speed and full noise levels - without going overboard with a monster PSU. But I would also like to know the exact CPU, RAM, drives, etc. Rico is using before assuming 650W would be better. It should be noted that PSUs are typically most efficient when running ~50% load. Now with a good quality 80 PLUS Gold PSU (I like EVGA SuperNovas), for example, we are only talking a couple percentage points between 50% and 100% or 50% and 20% load, but still, pennies add up. I don't agree based on the images I have seen - including the one in your link. That said, some heated air still goes back onto the case. But having worked with several Fractal Design cases, including the very similar R4 on this computer I am using now, the two 140mm fans that come with these cases are very effective at creating an efficient flow of air. I say try it first. If temps are not satisfactory, you can always add another fan later.
CPU = Xenon T3500 2.8 Ghz, not listed on above mentioned calc. I tried 3 - 4 of the listed Xenons & no diff. 8 GB I believe DDR3 1 cd/dvd rw note this is not-necessary, & no problem just not plug it in, from PSU, USB is fine & dandy No mouse or keyboard, for this machine. Monitor by VNC padded by choosing 4 fans Hmmm. Literature says this should be 2 hdd's, only one reported by win10, for the T3500, one small drive is sufficient. Software wise, used OO shutup win10 & all background apps, "OFF", this machine will be a one trick Pony, Folding@home, from Stanford University. Also a slower speed CPU would have been acceptable. Almost all 'protein FOLDING" is done by GPU. The machine & it's guts are in the original Dell case. I was mainly looking for a machine, that has two PCI x16 slots, & cheap.the goal is to retire a 32 bit folder, work units are becoming more rare for 32 bit, & UP the cumulative "CUDA" score, & improve work units to watts used. I just got this box, & the new parts will come after strategy is finalized. Also this machine will never get a new CPU. When dead trash! I found the Icrontic article, amazing almost unbelievable, how one rear exhaust fan trumps, the others. I believe the mounting support for missing 2nd (not needed hdd can be removed) wouldn't the 1070's one long & one short, improve air 'pathway'?
As good as it is the article is from 2003 when most cases had top mounted PSUs, among other differences, see this for a more modern approach.
Bill, you're wrong there, all open-air coolers will blow most hot air inside the case an that's by design.
That's because T3500 is Dell's "proprietary" designation, not Intel's. There are several Intel Xeon's that run at 2.8GHz. The Intel Xeon E5-1410 is one and the calc has that. Using that, two GTX 1070 in SLI, 1 HD and 1 CD and 4 92mm fans, the calc comes up with a recommended 575W PSU as seen here. So 550W is not enough. 650W would be a better fit. @Joxx. Okay, okay! "Most" instead of "some" like I said. I still believe the R5 is worth trying with the two 140mm fans it comes with. The FD 140mm fans when running at full speed move massive amounts of air (and are still very quiet as you noted). If they still do not provide enough air flow, the R5 provides lots of support to add more fans. No big deal.
Looking inside the box I find, current PSU is 525W, and comparing specs (manual) it seems to be missing one chassis fan. Missing hdd is ok as the current hdd is 2 tb, advertised two one tb sata hdd Fans after review, (ft. bezel was a bitch to get off) 120 mm cpu fan, & 120 mm fan, below, where 2nd (missing hdd) would be. Also this plug: (spare) 6 hole. could be supplemental power for one 1070, does an adapter exist to why off this, for feeding the 2nd gpu? Also the 120mm fan below missing hdd, blows directly, straight on, to both 1070's, or directly on to both pci x16 slots
Bill we differ by 50W, maybe I'm missing something? see: http://outervision.com/b/wPgRQy. Before your post, found/discovered the existing PSU is 525W. referring to post/reply #16 rear fans absent, what do you think one 92mm fan, blank off for 2nd fan, or two 92mm. I know this is just a wild guess, as front fans cfm is unknown, what rear cfm's for rear. If I'm correct: I would need 1 sata to molex power to one or two 92mm rear fan(s) 1 six pin (P5) male to female "Y" adapter, supplemental power gpu#2 2 gpus long short, two short, or long & short < 120mm fan ( below hdd cage) blows directly, head onto both slots pci x 16 Can you plug 8 pin adapter male into 6pin female? What are the two extra pins? 6pin female to two 6 or 6+2 'Y'. I can't remember if the GTX's card accepts female or male. I think it accepts female, not sure. Hence need 6pin male, the other end 6 or 6+2 female?
Please do not to assume one fan configuration will be best universally (eg the rear fan only as in the article I linked to) and that experimentation is needed to find the best fan configuration for the machine in question in this thread.
Thanks Bill, your correct! Got excited & started hunting for 80mm Fans & adapter cables, as I had ( 1 watt oversupply ), that R5 is looking better @Joxx reply post #18 shows 2 approaches. One 3 fan exiting to the case, while the one just 1 fan exits the rear. Seems like the one fan in the rear is more appropriate in my situation, do you agree. Also 1070's come in short version, do short cards blow into the case or out the back? @NGRhodes reply post #23 In a stock box (Dell etc) engineers calculate desired air flow, for normal usage. I'm way out of bounds, what engineers would consider normal usage. Still interesting & surprising article. Thanks!
