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miamicanes

Help. Computer adds 4-6 degrees to room temp. in new house.

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A few weeks ago, I bought my first house and moved in. Shortly thereafter, I made an unpleasant discovery... the bedroom I'm using as my computer room can't take the heat from my computer. Basically, the builder cut corners, and ran a duct that's way too small. Completely empty and unoccupied, the room is about a degree warmer than the rest of the house. Power up my desktop PC, with Athlon 64-X2/4600, Fujitsu MAU3147, and three more 7200 RPM hard drives, and within 10 minutes the room is 4-6 degrees hotter than the rest of the house, and unpleasant to be in for more than a few minutes. Oh, and that's WITH a ceiling fan.

In the long run, I'm going to have to pay someone a shitload of money to redo the ductwork. But I can't do that right now, because I'm semi broke. So, for now I need to do something to mitigate the heat problem enough to make the room usable.

For the record, I've already tried using longer cables and moving the case so it sits next to the door. It helped to cool down the room... but ONLY when the AC is actually blowing. Within a few minutes of cycling off, the room is hot again. It also caused a new problem -- because the thermostat is only a few feet away, the AC is influenced by the blast of hot air coming from the room and now runs until the rest of the house is frozen down to 69 or less if I leave it nominally set to 74 degrees.

In other words, I really do need to somehow reduce the amount of raw heat my computer is throwing off.

I initially thought about the CPU... but according to AMD, it's only throwing off 100 watts, max. The coolest CPU AMD makes is still 40 watts, and the coolest CPU that's no slower than the one I have now is 65 watts. In other words, I'd be spending a lot of money for slightly cooler operation.

That basically leaves the hard drives. I suspect my 4 drives are generating a LOT of heat, and that the Fujitsu drive is responsible for at least half of it. So... I'm thinking about removing all 4 drives from my computer, replacing them with a single 1TB Seagate drive (like the ST310005N1A1AS-RK, currently on sale at Best Buy) for daily use, and buying a pair of external enclosures for the 2 500-gig drives so I can use them as near-line removable storage (only powered up and running when I actually need to use them).

The big question is, is replacing 4 drives (1x15k, 3x7200) with a single 7200rpm drive really likely to make a significant difference in the heat being thrown off by my computer? Or will I just be burning $200 and sacrificing ~.95ms of seek time for no good reason? On paper, at least, it looks like the 1TB Seagate drive is almost as fast as my 15K Fujitsu drive... at least, in scenarios where you're comparing a system with multicore CPU and exactly one hard drive.

Edited by miamicanes

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http://www.xbitlabs.com/articles/cpu/displ...ut_8.html#sect0

Real-world numbers there-- you can save a good 40W to 80W of power easily there.

http://www.storagereview.com/WD3000BLFS.sr?page=0%2C5

http://www.storagereview.com/ST3300655LW.sr?page=0%2C5

As for disks, yes, 10-20W each operating, so going to a single disk will definitely have a measurable reduction in power consumption and heat output.

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For sure consolidate going to a single larger drive.

As for processor changes, it's a 90nm version right? I'm sure going to a smaller 65nm would be better, and well frankly every bit helps.

I think AMD overall system wise is still the leader when it comes to power consumption. While Intel may edge them out in some cases, when you factor in the chipset and RAM that Intel uses, they lose from an overall standpoint.

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That basically leaves the hard drives. I suspect my 4 drives are generating a LOT of heat, and that the Fujitsu drive is responsible for at least half of it.

I would have been more suspicious against the PSU efficiency and the GPU.

A right sized (stable) PSU with a 80+% efficiency IS a real gain and if you don't need a fancy gamer GPU buy a fanless one...

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http://www.xbitlabs.com/articles/cpu/displ...ut_8.html#sect0

Real-world numbers there-- you can save a good 40W to 80W of power easily there.

http://www.storagereview.com/WD3000BLFS.sr?page=0%2C5

http://www.storagereview.com/ST3300655LW.sr?page=0%2C5

As for disks, yes, 10-20W each operating, so going to a single disk will definitely have a measurable reduction in power consumption and heat output.

Hmmm. According to the chart, my CPU consumes up to ~225W when fully-loaded. HOWEVER, according to StorageReview's database, the MAU maxes out at ~19W, with most of the other drives hovering between 10 and 13 watts. And official ratings aside (that claim 2.9ms vs 4ms avg seek times), according to the database the MAU still thrashes every other sub-10k drive in existence at everything besides raw STR (seemingly getting double the performance at just about every other parameter).

That actually muddies things considerably. It suggests that the total heat generated by the drives (~50W) is almost insignificant compared to the amount thrown out by the CPU (225W), and that I'd probably take a MAJOR, painful performance hit if I sacrificed the MAU for a terrabyte 7200 drive. And more importantly, if I kept the MAU, but consolidated the other 3 drives into 1, I'd reduce the heat by a whopping 20 watts or so... more or less the heat thrown off by my desk lamp.

Sigh. I was kind of hoping the drives would be easy, low-hanging fruit... throwing off huge amounts of heat, and barely faster than a single big new drive. This seems to suggest otherwise :(

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update -- Just saw the newer responses. The GPU is a almost certainly a minor contributor... it's a GeForce 8500 or 8600 (ie, better than integrated... but not much). HOWEVER, I hadn't thought about the power supply. I'll be home from work in about an hour & check to see what brand/model it is. I think it's the 550-watt Antec one that CompUSA sold ~2 years ago.

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No easy answers to that one...you basically have a 550 watt heater running, in a small underventilated room, in a hot part of the US going by your sig.

I don't know the layout of your house, but might a window AC unit (a small, half window version) be possible? I used to have a very nice one of Japanese make that was rather quiet and small in one of my old apartments. Perhaps that might give some temporary relief until you can get the duct work straight.

Or, failing that, how about a large ducted fan blowing into the room from the hall? Even a cheap box window fan?

In short, with that computer, or any modern high-performance computer, you don't have much leeway for reducing the heat output. I would direct my effort into getting better and cooler airflow into the room. You don't need SR help, you need your local hardware store...

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In short, with that computer, or any modern high-performance computer, you don't have much leeway for reducing the heat output. I would direct my effort into getting better and cooler airflow into the room. You don't need SR help, you need your local hardware store...

Unfortunately, I think you're right. I was hoping the drives contributed disproportionately to the heat output, but it looks like that's really not the case after all.

For now, I guess the best I can hope for is to move the case as close to the door as possible so most of the heat will leave the room almost immediately, and maybe move the thermostat ~10 feet into the master bedroom. Right now, it's sitting in a direct line between the computer room's door and the air conditioner's main intake, so the hot air rushing by misleads it into thinking the house is hotter than it really is. If I move the thermostat into the master bedroom, it'll be on the opposite side of the air intake, and should get a more realistic view of how hot or cold the rest of the house is likely to be. The hallway is going to end up feeling like a furnace, but I guess it's the best I can hope for right now :(

<rant>

It's sad... for a state that would be uninhabitable without central air conditioning, most homes in Florida have systems that are designed like absolute crap, and intentionally ignore just about every principle of modern HVAC design.

Air returns are almost unheard of... most developers just cut a half inch off the bottom of interior doors, and stick the air intake in a relatively central location. It's EXTREMELY common, even in expensive (but not 100% custom) homes, to find air vents located next to (or even above) a door that's also serving as an air return, so the most natural path for the air to follow is straight down from the vent, then under the door and out of the room. And townhomes are the worst of all... the developers throw in single-speed central AC units that are oversized for the end units, and OUTRAGEOUSLY oversized for the middle units... so you end up with houses where the AC cycles on, runs for 5 minutes, then shuts off for a half hour, leaving you with air that's perpetually clammy, humid, and stale. Grrrrr...

</rant>

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Ideas:

1) Make sure there isn't a damper blocking the airflow to the

hot room.

2) Put a fan in the supply duct for the hot room, boosting

the air flow. They sell registers with booster fans.

3) Slightly close the dampers for the other rooms.

4) Make sure the AC fan is on constantly, not just when the

compressor runs. Note that the ceiling fan motor adds heat to

the room. Maybe you can get by without the ceiling fan if the

AC fan is on.

5) Does the hot room have a window with the sun beating on it?

Add a large roll down aluminum awning to shade the window in summer.

Full sun on a large window can be ~5000 BTU.

6) Inspect the attic and make sure the insulation is installed properly,

and that the attic is ventilated properly.

7) Get an energy audit. Bring in an infrared camera and see if there

is any insulation missing, or other problems.

8) Does the entire computer have to be in the same room?

If you can have the computer in one room and the monitor,

keyboard and mouse in another it will be cooler and quieter.

Or move the disks to a NAS in another room.

9) Do you have a CRT monitor? LCD monitors tend to use less power.

10) Get a power meter and measure the total power your computer

uses. Power off components (e.g. the 15k drive) and measure again.

11) <Kludge warning> If you don't mind the looks, you could use

drier vent ducting or large PCV and duct the heat output from the

computer down the hall to the AC return.

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Ideas:

2) Put a fan in the supply duct for the hot room, boosting

the air flow. They sell registers with booster fans.

11) <Kludge warning> If you don't mind the looks, you could use

drier vent ducting or large PCV and duct the heat output from the

computer down the hall to the AC return.

I was wrong about not needing SR help - we have some bright people in all sorts of manners here. Almost everything Konrad said was great advice, especially re-setting the registers. That will force the undersized duct to carry more of the load into the back bedroom.

The two I quoted above are also really interesting...didn't know they sold registers with booster fans, very cool.

But the idea of using dryer duct to conduct the heat out into another room or hallway is an EXCELLENT idea - very cheap, and very practical. For a bit more money, you could do the same thing with water cooling, and put the heat exchanger in another room - but not a cheap solution, so not very practical (and I say this as someone who watercools his PC).

I would seriously try the duct solution if possible. Just make sure your case is only using the exhaust fan in the power supply, and hook the duct up to that. You can always put a fan (120cm if possible, with filter) on the front of the case if you don't have one to help boost the airflow through the case and down the duct.

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An older Antec TruePower 550 EPS12V is probably only 72-75% efficient, you can upgrade to a modern unit that's 82-85% efficient (e.g. Enermax Pro82-series, the very latest from Seasonic, Corsair, PCP&C, etc.)... assuming a 250W peak load you're going to save another 20-40W there with the higher efficiency.

Again, as you noted with the harddisks, you're not getting huge differences here.,

According to the chart, my CPU consumes up to ~225W when fully-loaded.
NO! That's a TOTAL SYSTEM load. Your CPU is probably only... oh hell here's some CPU power numbers at full load and at idle.:

http://www.xbitlabs.com/articles/cpu/displ...e_10.html#sect0

You're probably talking only 105W at full load, not 225W, going to a newer 65nm AMD CPU would only save you 25-35W or so unless you went to a slightly slower 45W TDP Athlon X2 4850e or similar. Going to a Core 2 Duo E8200 or E8400 would save you significantly more power but would require a motherboard swap as well.

http://www.xbitlabs.com/articles/cpu/displ...e_11.html#sect0

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It is hard to say where the best cost/benefit would be without knowing how you are using your computer. When the computer is on, is there high CPU utilization and disk activity, like encoding video or distributed computing? This would make a big difference compared with a mostly idle computer, with web browsing and email like activities. Crunch the number to see what the best benefit would be for your situation. Here are some approximate numbers.

mode IDLE ACTIVE

CPU 15w 105w

10k 12w 15w

7200 8w 10w

MB/Vid 30w 30w (just guessing here)

Using these numbers your current system is using about 250 watts from the wall at 72% PSU efficiency when running all-out, and 113w when idle. You can see how much a difference Cool 'n' Quiet makes. You can go even further by undervolting your cpu, even under load. See silentpcreview.com for some good information on undervolting AMD cpus. I use CrystalCPUID on my Athlon X2 4600+ (939) system.

For a system with high CPU/disk activity, you will get the most benefit with a 45w cpu, saving (105-45)*(1/72%)=83w. The 65w cpu would save 55w. The next biggest impact would be going to a single hard drive, for 48w savings at the wall. Changing just the PSU for one that is 82% efficient at your target load, and you save 30w. Change the CPU and go to one hard drive for 132w savings, PSU and CPU saves 103w, and all three will give you a PC drawing 104w from the wall, for a savings of 146w. The numbers don't add up because the more efficient PSU saves you less power when you are using less power. This is a 58% reduction in the heat being pumped into your room, and you will feel the difference. Fan noise and energy consumption also goes down as an added benefit.

For a system that is mostly idle, the numbers change around since the CPU has the most dynamic energy use. In this case your PC is using about 113W from the wall. The biggest savings is going to a single HD, for 39w. Second would be a more efficient PSU at 14w, and third is the cpu at 6w savings. Combine all three and you have a system using 60w, for a 53w reduction at idle. This is a 47% drop, which would probably be noticeable. If this is your situation, it would probably be better to look at other sources of heat in the room, like sun on the exterior wall, a gap in the attic insulation, lack of trees shading the house.

Personally, I would start by combining the three 7200rpm drives to one, since you seem to have a use for the 2x500gb in an external enclosure. as a backup drive. Keeping the MAU for the snappy response may be worth a little heat. Once you start looking at a new PSU/CPU/HD, putting together a whole new PC while paying attention to energy efficient parts may be a better alternative.

I have always liked the idea of running the water cooling lines to an exterior radiator, but have never owned a water cooled PC to experiment with. I imagine the radiator would need to be oversized to compensate for the 100+ temperatures in the summer.

Good luck!

Mike

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