Quiet DIY OC'd Pentium D 830 System

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golemB
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Post by golemB » Wed Apr 26, 2006 11:47 pm

As before, awe is in order for your method, planning, execution, and documentation.

And thanks for your equally meticulous citation of forum suggestions!

zds
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Post by zds » Wed May 10, 2006 12:03 pm

Nexus at 7V significantly outperforms the AcoustiFan DustProof at 5V at about the same sound level. I guess the reason I had taken so long to try these fans is that I just don't like the color. Why can't they make some plain black ones like everyone else?
If you live in states, try this: http://store.yahoo.com/nexfan03/silent- ... sl-12.html

Unfortunately that counts me out :(.

And to the fan grilles: how about doing the classic trick, replacing the stamped ones with wire grilles? It should at least made them a lot less restrictive.

cmthomson
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Post by cmthomson » Wed May 10, 2006 1:36 pm

zds wrote:And to the fan grilles: how about doing the classic trick, replacing the stamped ones with wire grilles? It should at least made them a lot less restrictive.
I thought about this, and even bought a couple. But when I went to install them, I realized that the back vent grille was being used as the attachment point for some of the CPU duct sealing foam, and the top spoiler wouldn't fit over the circular grille. So I left the back alone, and covered up the top orange fan with a block of black foam on top of the spoiler (which also sucked up a bit of noise). Clunky, I know, but effective.

cmthomson
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Post by cmthomson » Thu Jun 22, 2006 1:56 pm

As summer approached, I became concerned about the high temperatures of my video card, a Gigabyte GV-RX80L256V with its stock passive cooler ducted to the motherboard fan. When running ATI Tool, the GPU temperature would climb above 120*C in about 10 minutes. Not good.

On a lark, I thought I would try an Aerocool VM-101 cooler after reading a review that extolled its cooling ability.

At first I tried installing it upside down (below the video card), hoping that the heat pipes would loop around the TV card, and I could use a shared duct to exhaust the heat from both cards. Unfortunately, the heat transfer block sticks out too far below the video card and intrudes into the PCI slot that the TV card was supposed to go in. Bummer.

So I installed it the way it's intended: with the fins on the solder side of the video card. Mounted this way, it hangs out over the north bridge, so it is incompatible with an HR-05. Here is a photo of it installed:

Image

As seen above, this cooler is huge, and spills into the slot below and at least two slots above the PCI-E slot it's installed in. However, its cooling is outstanding. My GPU temperatures dropped into the low 80s running ATI Tool with no change to the air flow.

Since I still wanted to evacuate the video card heat directly, I had to construct a new duct. I opted for a very simple duct consisting of two flat styrene panels. The other two sides of the duct are provided by the motherboard and video card PCBs. Here's a photo of the duct outside the system:

Image

and inside the system:

Image

The two diagonal bits on the outside of the duct divert air from the motherboard fan (visible at the right edge of the last photo) onto the north bridge heat sink.

This ducting arrangement worked well, pushing the GPU heat directly out the back of the case via an open PCI slot. It also had the unexpected side effect of dropping the reported motherboard temperature by 3 degrees, and raising the reported CPU temperature by 3 degrees.

The motherboard temperature change is fairly easy to understand since the airflow paths around the new video duct are simpler and smoother than around the old one. The CPU temperature change is a mystery, since the CPU fan is getting its air from a completely separate path from the motherboard fan. I compensated for this temperature shift by swapping the CPU and motherboard fan voltages, so now the CPU fan runs at 805 RPM and the motherboard fan runs at 770 RPM.

The system remains as quiet as before, but now the GPU is over 30*C cooler under load.

A couple of notes about the VM-101. As pointed out above, it is big: unnecessarily so. The screws that clamp the heat pipes to the heat block stick into the next PCI slot about 2mm, and the fins are so far above the back of the card that they intrude into a second PCI slot by a few mm or into the north bridge space, depending on what slot is used.

Also, when first installed, the heat block slides around on the GPU. This is easy to fix: wait a day for the rubber grommets to compress a bit, then retighten the nuts on the back of the card.

jaganath
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Post by jaganath » Fri Jun 23, 2006 2:12 am

A couple of notes about the VM-101. As pointed out above, it is big: unnecessarily so.
Is it really "unnecessarily" big? If you want better cooling you have to have either better airflow or better surface area, or ideally both. There is a trade-off here, and size is it.

cmthomson
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Post by cmthomson » Fri Jun 23, 2006 5:43 am

jaganath wrote:
A couple of notes about the VM-101. As pointed out above, it is big: unnecessarily so.
Is it really "unnecessarily" big? If you want better cooling you have to have either better airflow or better surface area, or ideally both. There is a trade-off here, and size is it.
Yes, it's unnecessary. The heat block could be a bit lower, and use recessed screws; that would get rid of the interference to the slot below the video card. The fins could be a bit closer to the board (they are way above it); that would avoid spilling into yet another slot above the card.

I'm not suggesting making the fins smaller, just making the overall dimensions less profligate of slots.

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