My 785G passive 240e & Dell RM112 build

Show off your quiet rig.

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flyingsherpa
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My 785G passive 240e & Dell RM112 build

Post by flyingsherpa » Sun Mar 28, 2010 7:12 pm

So I finally upgraded, woohoo! I was coming from an athlon xp-m 2400+, so this is a big boost. I mainly decided to upgrade because I was getting increasingly annoyed with being unable to play more and more videos I ran across. I lasted 5.5 years on the old system, not too shabby. New specs:

- Athlon II 240e (45W)
- passive Xigmatek Dark Knight heatsink, mounted vertically via Enzotech backplate
- MSI 785GM-E65 motherboard
- Cooler Master Elite 341 mATX case
- Dell RM112 235W 80-plus Gold PSU, hacked into ATX form factor
- 4GB G-Skill DDR3
- Lite-on combo drive
- Hauppauge HVR-2250 dual tuner
- WD6400AAKS hard drive (only part carried over from previous PC)
- Windows 7 x64 Pro

The Dark Knight is an absolute thing of beauty, especially without a fan strapped to it. It is also surprisingly light for its size. Mounting it vertically on an AM3 socket was a royal pain in the ass (took 3-4 hours!), but necessary to retain access to all RAM slots and for better "passive" (read: case air flow only) operation. I had to buy a special new backplate (Enzotech), dremel off some tabs of the socket 775 mounts, find tiny 3mm nuts, and screw them down by feel only (no spring tension to guide me). So I'm sure the pressure isn't perfectly even, and it's scary when you're not sure how hard you should crank down, but it is very secure and performing very well so far. I'm running it passive... it takes up such a large part of the cross section of the case that air pretty much has to pass through it. Cooler Master advertises the max heatsink height to be 160mm for this case. The Dark Knight spec is 159mm. It actually just grazes the side panel. Kind of scary, but it technically fits. I was sweating that one as I knew it'd be close.

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I knew I wanted mATX, but I couldn't find a case I liked. The NSK3480 was close, but seemed a bit too short in depth... I like to put my hard drive on the case floor in front of the intake and it just didn't seem like enough room in the 3480 if you have a PCI slot filled. Also, I didn't want to pay for the PSU I wouldn't use, and I prefer an open interior as opposed to its divided one. The CM Elite 341 is a decent case, I think, especially for the price. It looks better than its pictures, anyway. The intake is pretty open so it could be a direct path for sound to escape, but my build is quiet enough that it works ok for me.

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I cut out the fan grills. I didn't do a great job, but no one is going to see it so I don't really care :P . I used tin snips, maybe I should get a nibbler (the snips tend to deform the material around it and leave sharp jaggies here and there that have to be dremeled).

I used magnetic sheeting to dampen the case panels. It seems to work pretty well (knock test before and after shows more of a dull thud after application) and has the advantage that you can slide the sheets around to cover or uncover venting on the side panel to easily change the airflow. Also, you can easily remove it if you want. I used sheets from Staples which are a bit too thin... I've found some online for like $10 that are much thicker (used for advertising signs on cars) that I might try someday. I recommend this method over bitumen or tar-based solutions... I've used some in the past and they always slowly slid down the panels and made a huge ugly mess. Notice that i had to cut slots in the 0.030" sheeting for the tips of the Dark Knight's heatpipes... the clearance was that tight!

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Here is the custom PSU. I was going for low power consumption so the Dell RM112 was too good to pass up as it's supposedly 90% efficient even at low loads. Yeah, it's probably only a few watts difference over a bronze one at that load, but I got a bit carried away. I pretty much copied what BillyB did here. Thanks to forum member trident for donating an empty ATX PSU shell for this. I'm really happy with the results, but it was a ton of work soldering and cutting and grinding and mounting everything. I easily spent over 10 hours on this part. If I knew it would be that hard I wouldn't have done it. My craftsmanship doesn't look as clean as Billy's, but again no one will see it, it's very secure, and it works so I don't really care :P. Note that I mounted the RM112 approximately in the middle of the ATX PSU chassis... I did this on purpose so that the extra length of the RM112 wouldn't block the connectors of a 5.25" drive in the top bay, should I ever want to add one.

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Btw, while I was modding the RM112, I ran the machine for a few weeks on a 300W PSU that came with an old Enlight case I bought years ago. It idled around 58W. The RM112 idles at 30W. What a difference efficiency makes! Though as soon as I fire up Firefox (with my standard 3 windows and 15-ish total tabs) it tends to idle at 45W, perhaps some flash or something is running on some of those pages, I should investigate that). In S3 sleep the PSU pulls 2W.

I know most people like suspension, but I usually prefer resting my spinning platters on foam and sorbothane. The foam is mostly there to raise the drive high enough to get more airflow from the main intake. I closed off all the other holes in the case (with magnetic sheet or tape) so all air comes in through that hole. The drive is still a little low and so runs warmer than it did in my old case (with a fan directly on it), but it's in the range that Google's study claimed was ideal so I think I'll leave it be.

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Ventilation is by two Scythe S-flex 120mm 1200 rpm fans, one on the rear case exhaust and one in the PSU. I usually use hardware fan controllers, but everyone was out of stock on the one I want so I'm trying Speedfan for now. It doesn't seem to work reliably after waking up from sleep (it will still report temperatures, but no longer auto-controls the fans. It also never sees my hard drive). I have some fanmates I may use for more testing.

I know my cabling isn't the best, but it's better than my last PC and it's good enough for me :P. I'd have to add an extension cable to the PSU connector if I wanted to route it any different and I'd rather not do that.

Bottom line: This setup is very quiet and cool and energy efficient. Performance is a huge jump over my old rig and Windows 7 seems mostly good. With both fans around 800rpm, it idles at 30-40W with the CPU at 36ºC and a 2xprime95 load draws 80W with CPU at 48ºC. It also sleeps and wakes in about 10-15 seconds... my old rig had slowed to taking several minutes to do that for some reason.


Wow, that turned out longer than I thought. Questions or comments are welcome.
Last edited by flyingsherpa on Mon Mar 29, 2010 5:46 pm, edited 1 time in total.

flyingsherpa
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Post by flyingsherpa » Sun Mar 28, 2010 7:14 pm

A little PS - This is my main computer, but my apartment's layout makes it fairly easy for it to do double-duty as a HTPC (just run some cables through a half wall). I have a tivo and dvd player, so the only HTPC-like tasks I do is stream netlix movies or play videos I don't have on dvd or that the dvd player can't handle. I'm not HD yet, so I use this Sabrent box to convert the motherboard's VGA to s-video into my A/V receiver and then into my 480p front projector. It works pretty well, though my projector is 854x480 and the Sabrent box only allows standard resolutions like 800x600 or 1024x768. I haven't used it too much to know if this is a big deal or not... the test videos I played looked decent, about as good as my old rig with a discrete card that had an s-video out. One other niggle: the 785g motherboards don't seem to allow simultaneous audio output to both spdif and analog. I have analog going to my PC speakers, and spdif optical going to my receiver for HTPC duty or louder music listening, and I have to manually change the settings from analog to spdif each time I want to switch. My old mobo output to both all the time. Grrrr.

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The HVR-2250 tuner rocks, especially with Media Center. It pulls in several HD clear QAM channels so I can actually see HD feeds on my monitor. I'm still sticking with my old SD Tivo (without any converter box) for my tv for now, but that could change if I ever get an HDTV.

frostedflakes
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Post by frostedflakes » Sun Mar 28, 2010 10:14 pm

Nice little system, good work on the PSU mod. :)

Would be so much easier if you could just buy adapters for the ATX connector and back plate, though. I bet a lot of SPCR users would be interested in this PSU if it didn't take so much effort to install in an ATX case.

bozar
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Post by bozar » Mon Mar 29, 2010 1:20 am

Great mod.

porkchop
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Post by porkchop » Mon Mar 29, 2010 3:13 am

the things we do for low-noise and efficiency :)

flyingsherpa
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Post by flyingsherpa » Mon Mar 29, 2010 8:13 am

Thanks for the comments!
frostedflakes wrote:Would be so much easier if you could just buy adapters for the ATX connector and back plate, though. I bet a lot of SPCR users would be interested in this PSU if it didn't take so much effort to install in an ATX case.
I totall agree... I actually contacted a bunch of vendors who are selling the inverse of this (i.e. an adapter to use a standard PSU on a motherboard with a mini 24-pin connector) and none of them had heard of anyone having the adapters we'd want. Sigh, I guess we are a small market.

frostedflakes
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Post by frostedflakes » Mon Mar 29, 2010 8:45 am

Unfortunately for us, people upgrading their Dell PSU to standard ATX is a lot more common than people trying to fit proprietary Dell PSUs in regular cases.

I've searched as well and the appropriate adapters just don't seem to exist.

c.ruel
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cable management

Post by c.ruel » Tue May 11, 2010 8:21 am

I have the same case as you and I have an absolute nightmare with the cables. Looking at how neat your cables are I now know what my problem is, my optical drive is really long for some reason. Really nice build and must be way quieter than mine lol. I'll have to buy a new optical drive and see if I can get my cables as neat as yours!

Rebellious
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Post by Rebellious » Tue May 11, 2010 9:09 am

Which Enzotech retention module did you use? The Type-X AM2 comes with built-in bolts and there is no need for modding/dremeling.

http://www.performance-pcs.com/catalog/ ... s_id=22796

flyingsherpa
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Re: cable management

Post by flyingsherpa » Wed May 12, 2010 9:19 am

c.ruel wrote:I have the same case as you and I have an absolute nightmare with the cables. Looking at how neat your cables are I now know what my problem is, my optical drive is really long for some reason. Really nice build and must be way quieter than mine lol. I'll have to buy a new optical drive and see if I can get my cables as neat as yours!
Yeah, I probably have a short optical drive and psu case (well, except for the part sticking out). But what really helps is that I have so few wires. I only soldered on what I needed, so I don't have a bunch of spare ones to try to hide. If I had to upgrade my psu, I would buy a modular one so I could have a similar benefit without having to wire it by hand.

Rebellious, I think that is the retention module I used. I didn't have to dremel that, it was the Dark Knight's mounting clips that needed shaping. They were designed to fit one way only for LGA775, forcing them the other way to use with the Enzo plate required grinding off the tab so they could be used "upside down".

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