While this may work, you effectively reduce the surface area for the thermal transfer to the size of the box. I suspect an oil cooler would have a larger surface area, and for my setup at least, its much easier to drop a cooler in my existent filters where I already have waterflow, than create a box and somehow circulate large amounts of water through there without overflowing it due to pump head. With gravity return that means HUGE pipes or low flow.  You would also risk a fair amount of water evaporating in a place where I dont want humidity, ie, in the shed where my rigs are.

The idea of an ammo box is excellent though.


Oh, and no zinc in the water. My Koi dont like it


Yes, the problem is thermal grease can be conductive. You dont want it dissolved in the oil. But indeed, for temperatures it should not be a big concern as it would be replaced by oil.  To make sure no air gets trapped, you will want to smear some oil on the die before re-mounting the heatsink.

Its not so far out of the box, since I got the idea while reading about mineral oil often being used to seal other liquids. So why not vegetable oil
Anyway, Ill go shopping this weekend and Im buying some extra parts to build a rig around an old 8800GT to experiment with.

Some other points I came across:
- thermal grease will dissolve in oil. Before plunging in the cards, youlll have to remove all thermal grease. I hope the vrm pads will manage.
- I came across one report of overheating with a S775 CPUs, despite the oil being cool. apparently caused by air trapped in the socket; though Im not quite sure I understand how that would work, Im assuming this is not a problem with GPUs as there are no sockets.

INdeed, you posted all 3. Still its worth pointing out that your 850/300 temps are unsurprisingly lower than your 960/300 temps despite lower fan speeds, so my point stands. Its also a fair point to make that gaming cards are not designed to run what AMD would consider a thermal virus 24/7. Professional compute cards from AMD and nVidia (firepro and quadro) are mostly based on the chips as the gaming cards, but they generally run at lower clocks and voltages. These cards are designed to run 24/7 at max load.

Ive been reading and searching further on this subject to decide on the oil. I can not find a cheap local source of mineral oil, so Im gonna go for vegetable oil. Im aware this is less stable and can oxidize (go rancid). It seems the biggest factors contributing to oxidation are sunlight and humidity. The first is easy enough to tackle, I have no need for a transparent aquarium, by setup is going to be butt ugly anyway.

To counter humidity, Im going to try to add a layer of mineral oil on top of the vegetable oil as sealant. Mineral oil is lighter and should therefore float on top, but Ill have to see if it mixes or not.

If anyone has other suggestions, Im all ears. Is there something lighter than mineral oil that is stable and not conductive to use as sealant?

Obviously not. Both current and temperature are key exacerbating factors of electromigration. Clockspeed afaik, is not. But its a false dilemma, because a higher clockspeed will result in higher temperature and require higher voltage, regardless of what your testing shows (hint: there are several temperature sensors in the GPU, you are measuring only one, quite possibly GpuIO which is the memory controller. Try checking the shader sensor).

As RJK mentioned; those are the worst, because of the design. Its 2 slots and 2 sockets.
Without extender, so plugging a card straight in to the motherboard, you have a single non-soldered socket. With a regular extender cable you have 2. With your clumsy extender there are 4 per device!

Its not just length, there is much more to it. Just the fact you have a connector is a huge issue and greatly limits clockspeeds and can introduce all kind of problems. There is a reason soldered GDDR (vram) is so much faster than socketed DDR ram (and a reason you can not socket GDDR).

UEFI; no not likely a factor. But you may have a point, if the motherboard has a PCIe switch onboard, it may give you less headroom to use extenders. Extenders do not conform to the PCIe spec, it just exploits some headroom, but there might not be enough on complex boards with long traces or perhaps slightly more crappy PCIe controllers.

Do you get the ubuntu splash screen before it turns black? Can you SSH in to the machine? Does the numlock still turn on and off?
Have you tried booting with nomodeset

Pfft. Nitpicking. And really, it did you a favor

And its not like videocards that are not used for mining ever die 

Its really simple, any silicon chip thats used will eventually die. Its a given. The only question is how long it will take. It could be centuries, it could be days. But stressing these chips will reduce their lifespan, particularly when overvolting and overheating. If you are lucky, you may never notice, but it doesnt change the facts.

I might believe for used 5970s prices bitcoin mining is perhaps not entirely irrelevant, after all, this is a really niche product and really attractive for mining. I dont know how many AMD ever sold, but to put this in perspective, the entire bitcoin network represents only ~10.000 5970s. Considering AMD sold millions of cypress based cards, bitcoin really is not that important in setting prices. For 7970, Id be shocked if 1% was bought for mining.

Here, another datapoint:

In the very near future, as we overcome supply constraints, we will be increasing shipments of 5800 series graphics processors by roughly an order of magnitude, moving from thousands of units shipped per week to tens of thousands.  This should alleviate some of the pent-up demand.
http://www.hardwareheaven.com/news.php?newsid=322

So the entire bitcoin network represents roughly 1 week worth of AMD 58x0 sales.

I have no idea if it will be any good for mining; but mining is like 0.1% of the highend GPU market, if that, its not setting prices. If list prices of 7970s plummet to $299, its not gonna help your resale value for a used one . And $299 in a few months is pretty much a given, at least if you believe semiaccurate, a site notorious for bashing nvidia and cheer leading ati, yet they claim Kepler will run circles around the 79x0 cards and launch at $299.
http://semiaccurate.com/2012/01/19/nvidia-kepler-vs-amd-gcn-has-a-clear-winner/

(price is mentioned elsewhere)

I dont think resale value of the 7970s will be much better. It is of course now, but expect those prices to implode once nvidia's Kepler hits the market in a few months. Better hang on to those 5970s IMO, far better MH/$ now and comparable (if not superior) MH/W depending how much you can undervolt either card.

Just curious, what was the problem?

Pool is down.

ozcoin is down too. Could it be a DDoS attack? most other big pools appear to be working though.

While the website is down, the backend still seems to work. Im not seeing any real problems?

For the most part, all these cards do indeed use the same fan (although Ive seen slight variations in amperage/wattage). The lowest end cards usually have a different non ref cooler, 5450s even tend to be passive, but for the cards that matter, these fans can be interchanged - for reference coolers.

Sounds like you have too many potential sources of problems. If I were you, Id start by plugging in a single card, with no extender cable and see what happens. If that magically solves all problems, slowly build form there, by adding the cables and extra cards and see when the problem occurs.