Haswell heat-minimisation advice

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Hrafn
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Haswell heat-minimisation advice

Post by Hrafn » Thu Oct 31, 2013 6:20 pm

Hi. I'm looking at the possibility of building a smaller, cooler-running, and hopefully quieter system. It will be used mostly for watching videos and web-browsing, with some light gaming and occasional bouts of video transcoding. I'm currently running an i3 2120 (TDP 65W), which seems to handle my needs fairly well (though who will say no to some extra grunt). The problem is that I have to leave the window open in my room day and night through much of summer.

I'm planning on building it in a mATX case (most probably a TJ08B-E), so a reasonably-sized tower HSF is not a problem (although the 15mm overhang from the heatsink on my passive GPU probably reduces the maximum HSF width from 14cm to 12cm). The issue is heat output (mostly idle-light utilisation, but occasionally heavy-maximum).

The choices appear to be:
1) A normal Haswell i3 (TDP 54W), most probably a 4130 (but that may change according to price differentials)
2) An (apparently factory-undervolted/underclocked) i5 4570T (TDP 35W)
3) Manually undervolting and/or underclocking (does the latter require a K-suffix processor?) some other CPU to match this ballpark performance.

Can anybody give me ballpark wattages for these 3 options at idle-light and heavy-maximum utilisations? And what CPU would be most appropriate for the third (assuming a neophyte underclocker)? The 4570T is clearly the most expensive option, but I'd like to get some idea what the wattages are at each price-point before making a decision.

Also, is there much of a difference in the power draw between mATX Haswell MBs (assuming that I'm not buying an all-the-bells-and whistles OCing board)?

Abula
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Re: Haswell heat-minimisation advice

Post by Abula » Fri Nov 01, 2013 9:42 pm

Are you sure its worth moving to haswell for you? the difference from both i3 should be like 10%, unless you are in for the iGPU but you seem that will be using a dedicated GPU, for this you will have to change motherboard and buy a new cpu, maybe memory. Would end up cheaper just to rebuild what you have atm, and if you want to change the size into micro ATX, there are plenty of ivy bridge motherboards that should run fine your i3.

But if you think its worth the upgrade, then here are my comments and question,

1) CASE
The TJ08-E is a wonderful case, really nice, i used one for two years and very efficient for cooling, but the frontal fan is very loud at 12V (1200rpm), even with the low switch (900rpm) is still very noticeable, around 700rpm becomes tolerable, and 500rpm is where i used mine lately, very quiet at this speed. So if you are perusing a quiet setup, be ready to have to undervolt the frontal fan a lot, either by external fan controller or chose a motherboard like Asus for FanXpert2, the following is the graph of the AP181 (frontal fan of the TJ08-e) on an Asus Maximus IV Gene running FanXpert2, i believe the ASUS H87M-PLUS has also fanXpert2 for cheaper alternative on micro atx.

Image

Another alternative, if you like the size of the TJ08-E, is the Silverstone PS-07, which its internals are exactly the same (i also did a build for friend on it), the main changes are the front is plastic and has a door and instead of 180mm fan there are two 120mm fans, this will widen a lot of choices of motherboards and fans, for example you could go with MSI or AsRock with better PWM fan control and get 120mm PWM fans.

2) GPU
You mention a passive cool gpu, do you have one in mind? this is important also not only for the heatsink but for chosing the PSU.

3) Motherboard
There are option in micro ATX that dont have the first PCIe on the first slot, but on the second, ill leave you a couple of examples that could allow you to use a bigger cpu heatsink and still use a passivly cooled GPU that extends some to the back (this you will have to crosscheck once you decide the other components).
Intel BOXDB85FL LGA 1150 Intel B85 HDMI SATA 6Gb/s USB 3.0 Micro ATX Intel Motherboard
Intel BOXDH87RL LGA 1150 Intel H87 HDMI SATA 6Gb/s USB 3.0 Micro ATX Intel Motherboard
Also, is there much of a difference in the power draw between mATX Haswell MBs (assuming that I'm not buying an all-the-bells-and whistles OCing board)?
The most efficient motherboards in my experience have been intel, but the difference isnt as much as to jump to a bigger PSU, single digits. MSI is also pretty solid on consumptions, specially the B85M-P33 (this is not a standard micro atx is slightly smaller).

Ill try tomorrow when i have better light to lay over the NoFAN95 on my TJ08-E that still has the Asus GENE mobo on it for you to get an idea into how it would fit and how much it will need in space.

Hrafn
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Re: Haswell heat-minimisation advice

Post by Hrafn » Fri Nov 01, 2013 11:42 pm

Abula, let's clear the irrelevancies out of the way:
1) No, I won't be putting my existing CPU into my new build. This would (i) mean that I'd lose access to a working computer while rebuilding (problematic, if something goes wrong) & (ii) I would be left with close to everything but a CPU in old parts (far easier to sell a full old build).
2) My question was not about the case. That was mentioned merely for context (i.e. that average heat output was the relevant decision variable, rather than limitation on the maximum heat my build could dissipate being a binding constraint). (Parenthetically, I have already looked at the PS-07 and am already aware of the noise issues with the stock front fan on the TJ08-E).
3) The fact that I gave a mm-precise measurement of the overhang of my GPU should have given some clue that I already own it. In any case, it was listed contextually as a (very minor, and likely non-binding) constraint, not as a decision variable.
4) I'll keep in mind the Intel MBs, when I get around to making a decision on a MB/HSF combo (but will have a large number of criteria beyond placement of the GPU slot). And no, this combination will not include a NOFAN cooler (which I was also already aware of).

Now that this is out of the way, I think I asked a question. Let me see, what was it? Ah yes ...
Hrafn wrote:The choices appear to be:
1) A normal Haswell i3 (TDP 54W), most probably a 4130 (but that may change according to price differentials)
2) An (apparently factory-undervolted/underclocked) i5 4570T (TDP 35W)
3) Manually undervolting and/or underclocking (does the latter require a K-suffix processor?) some other CPU to match this ballpark performance.

Can anybody give me ballpark wattages for these 3 options at idle-light and heavy-maximum utilisations? And what CPU would be most appropriate for the third (assuming a neophyte underclocker)? The 4570T is clearly the most expensive option, but I'd like to get some idea what the wattages are at each price-point before making a decision.
I cannot help noticing that if somebody asking a question fails to give context, they tend to get told that an answer cannot be given without the context. But here, where context was given, all it did was cause the answerer to be distracted away from my actual question. :roll:

Vicotnik
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Re: Haswell heat-minimisation advice

Post by Vicotnik » Sat Nov 02, 2013 5:46 am

In a roomy mATX case like the TJ08B-E and with a good HSF you will be fine with any i3 out there. How is it that you have heat issues with your current setup? Without context it's difficult to help.

Also, some courtesy goes a long way here. The "normal" vs "factory underclocked" CPU dilemma has been discussed over and over and over again. Short answer: get the normal one.

Hrafn
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Re: Haswell heat-minimisation advice

Post by Hrafn » Sat Nov 02, 2013 6:39 am

Vicotnik wrote:In a roomy mATX case like the TJ08B-E and with a good HSF you will be fine with any i3 out there. How is it that you have heat issues with your current setup? Without context it's difficult to help.
I had thought that I'd provided the context in my first post. The problem is not heat dissipation from the case, but heat dissipation from the room (which is smaller, better insulated and in closer proximity to nocturnal insect life than the room for which the current system was originally constructed). Hence, total (average) heat output becomes the driving issue, hence my original question.

I'm therefore looking at the possibility of replacing my ATX case with its solid-cheap-but-not-amazingly-efficient PSU and its current CPU with an mATX case, considerably more efficient (but more expensive) passive/semi-passive PSU and (if possible) a more efficient CPU. The first two parts of that equation are not difficult to find information on, so I was asking only about the third.

(If I cannot combine a more convenient size with a sufficiently substantial total heat improvement, I may put off upgrading until a more compelling reason comes along.)
Vicotnik wrote:Also, some courtesy goes a long way here.
I apologise if I was overly terse, but I was frustrated by a response that talked about everything but my main question (including a lot of stuff that I'd already found out about).
Vicotnik wrote:The "normal" vs "factory underclocked" CPU dilemma has been discussed over and over and over again. Short answer: get the normal one.
Then you can perhaps direct me to the FAQ on this question that has been clearly "frequently asked"? It was quite easy to find threads discussing the rival merits of the TJ08B-E and PS-07, and the demerits of the AP181 (hence my profound disinterest in being further educated on these topics), but I've yet to find anything that either (i) gave the analysis underlying the "short answer", (ii) mentioned whether/how the recent Intel restrictions on overclocking affected this equation, (iii) what clockspeed 'overhead' you should allow for an optimal underclocking or (iv) what order of benefit you garner from the whole exercise.

If you can point me to a FAQ, or even some threads, that answer all/most of these issues, then I'll happily go back to lurking on these fora, and darken your doors with my obstreperousness no more.

flemeister
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Re: Haswell heat-minimisation advice

Post by flemeister » Sat Nov 02, 2013 6:59 am

http://www.silentpcreview.com/article1202-page3.html

That's a comparison of the i5 2400, i5 2400S, and an undervolted i5 2400 for idle and load power consumption. As you can see in the graphs, there is little/no difference at idle, but a notable difference under heavy load. Note the clock speed difference between the i5 2400S and the undervolted i5 2400, which explains the 4W difference under load. Drop the regular i5 2400 down to 2.5GHz and undervolt a bit more, and you'd surely close the gap.

The same applies to a Haswell CPU. Get a normal model, and undervolt/clock it yourself. That way you've got the ability to bump the clock speed back up if you ever want to in the future.

As for CPU and motherboard's supporting undervolting/underclocking, even the locked model CPU's should be able to have their multipliers lowered (overclocking not allowed, underclocking allowed). Most motherboards support undervolting/underclocking, although IIRC some Gigabyte H77/Z77 boards didn't allow undervolting (just their mini-ITX boards I believe). They enabled it again with their mini-ITX Haswell boards though. :roll:

Pappnaas
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Re: Haswell heat-minimisation advice

Post by Pappnaas » Sat Nov 02, 2013 9:20 am

Instead of using the language you chose, a more fact driven approach would be easier to understand.

Question:

Why does a SB-based i3 rig force you to leave the window open? How high is your room temp with PC off and with PC on?

How much wattage would the total new system consume less and how much heat would not be created?

Talking about 11W TDP@CPU@load and the rest of the system, for the arguement's sake let's assume the total new rig saves around 25W@load and 15W@idle.

How much of a difference would 15-25W less make in your room? And how much would you spend?

edh
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Re: Haswell heat-minimisation advice

Post by edh » Sat Nov 02, 2013 1:45 pm

Pappnaas wrote:How much of a difference would 15-25W less make in your room? And how much would you spend?
Idle power for a human body is often considered to be around 120W. This means the user is going to be of greater concern in terms of heat than the system itself. You could always spend more time outside of your room... Some people could also make a greater than 15-25W impact on reducing their own heat output simply by losing weight.

I have to say I side with those here who question the need for such an upgrade.

Hrafn
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Re: Haswell heat-minimisation advice

Post by Hrafn » Sat Nov 02, 2013 6:34 pm

Pappnaas wrote:Why does a SB-based i3 rig force you to leave the window open? How high is your room temp with PC off and with PC on?
I tend to open a window when the temperature rises above 25C, which has happened only once this (Southern hemisphere) spring (26C). The temperature in my room at the moment (having recently turned my computer on) is 21C.
Pappnaas wrote:How much wattage would the total new system consume less and how much heat would not be created?
Estimated current (max, idle likely to be somewhere 25-50% of that):
CPU: 65W (going off TDP as first approximation)
GPU (HD7750): 45W
Harddrives: 40W
Other (MB, memory, etc): 45W
PSU (Huntkey Jumper 550W, efficiency reported in low 80%s): 40W
(Total somewhere in the range of 240W)

Biggest 'easy' saving would be 20W by upgrading to a gold/platinum PSU. CPU saving is what I've been asking about (minimum saving 11W from SB->HW). That's somewhere in the order of a 12% saving (before undervolting). That's not enormous, but not insignificant. (Beyond that, I'd have to look at eliminating the GPU and running off integrated graphics.)

On the underclocking/undervolting side, it seems that underclocking does not directly improve efficiency (Wh/cycle), but rather (i) reduces the maximum draw & (ii) possibly allows more room for stable undervolting. I've seen reports of 12% undervolting (resulting in 25% power savings), but the whole thing seems to be very motherboard-dependent. However, as information on this ranges from sparse, to purely anecdotal, its hard to get a solid read. (It also seems that 'T's perform no more poorly than their manually-underclocked unlettered equivalent, just that you pay a slight premium for having Intel do it for you. Also, the 4570T is an oddball in not being an underclocked 4570, its more like a hybrid between an i5 and an i3.)

I'm going to have to upgrade to a mATX at some stage (ATX really doesn't fit its current location), but will probably have to look for a more compelling 'excuse' than power savings for doing so.

HFat
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Re: Haswell heat-minimisation advice

Post by HFat » Mon Nov 04, 2013 4:13 pm

Manual undervolting can result in instability. Unless you undervolt way too much (instant crash), it's not always easy to tell because it can leads to very infrequent errors and crashes. In principle, it can lead to all sorts of nastiness including data loss. Do you really want to take chances?

The actual CPU part (not the whole chip) will consume less Wh/cycle underclocked. The whole computer will often not be more efficient at crunching numbers because of the power consumed by other parts. Whether you should underclock depedends on whatever you want to achieve.
Safe undervolting happens automagically now. The CPU's going to idle at 4W or something equally insignificant anyway. Your wattage numbers are way off from what you'll get in practice. Intel's TDP values are off in most cases. Nowadays non-gamers typically run their new computers on less power than a human being dissipates... at idle, not infrequently an order of magnitude less!
The CPU stuff isn't worth fussing about in most cases unless you want to run it at 100% a lot of the time. Get a fancy motherboard that undervolts and see its oversized VRM and whatnot burn power. Or maybe not. I hardly care so my rule-of-thumb might be out of date.

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