Chihiro GPU fan monitor and other maintenance concerns

[winteriscoming]

Recent Chihiro discussions have lead me to believe they might be more susceptible to failure than I had thought. Apparently a common failure is that the GPU fan can die and the GPU cooks itself and the surrounding PCB, making it virtually impossible to repair.

What about adding in an external GPU fan monitor that shuts down the Chihiro if there's a fault?

It seems like it could be a relatively simple and cheap Arduino project. Here's an example of reading a fan's RPM with an Arduino.

So the circuit could involve wiring up the fan's signal wire to the Arduino and routing power (maybe just 12v?) to the Chihiro though something like a relay. The Arduino would be responsible for allowing the Chihiro to power on. If it senses a fault in the fan, it kills the power.

Questions:
1. What type of fan is currently in use for the GPU? Is it one that has a signal wire? If so, does the Chihiro require that the signal wire is hooked up in order to boot (also if it does need it, why doesn't it monitor and shutdown in a failure!? )? If not, is there an adequate replacement that does have a signal wire that could be used by the Arduino?
2. What has to be done to sufficiently kill Chihiro power and avoid damage? Is cutting 12v sufficient? Do all three (3.3v, 5v, and 12v) need to be cut to safely turn it off in a fault scenario? I wouldn't want to go all the way back to cutting AC since the Arduino would likely need to be powered by the power supply using that same AC.


What are other failure points that merit maintenance? I have read about removing a memory cap, but haven't found a clear guide on which cap to remove.

 

[winteriscoming]

I just opened up one of my Chihiros to see the GPU fan. It's a 40x40x10mm fan with plenty of vertical space, so a thicker one than stock should fit fine. It's a 2 wire type, so no RPM monitoring.

This makes me think an RPM monitor would be a very feasible solution to work into the Chihiro. Just get an appropriately sized 3 wire fan and route the yellow wire to the Arduino that monitors the RPM. Then route the power through some kind of relay that the Arduino cuts if the RPM gets too low. There might be space enough inside the Chihiro to install within the Type3 case, and perhaps intercept the power at the ATX connector...

 

[obcd]

The memory cap is a 1 farad goldcap. It usually starts to leak, and the stuff coming out is corrosive for the pcb tracks. The original xbox used it to keep it's clock going for a couple hours with the main voltage unplugged. It's on the left side of the pcb, close to the front border of it.

The bigger fanless heatsink used on xbox 1.1 - 1.6b mobo's (on the gpu) doesn't fit in a chihiro setup. The base board is 2 close to the main board and the heatsink doesn't fit between them.

On the power connector, there is a wire that is used to turn the power rails on and off (all 3 of them) On an ATX supply, you need to connect that to GND so that the supply turns on. The xbox and chihiro supply need a voltage on for the supply to turn on. I just don't know if it's 3V3 or 5V it needs. You have a standby voltage that remains present, even with the other voltages turned off. It could be used to power the arduino.

 

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I snapped some pics:

Motherboard:
This is oriented such that the filter board would be facing the bottom of the pic when installed. The memory cap is located to the lower right.


GPU Fan:


Memory cap:

 

[twistedsymphony]

After V1.0 the retail Xbox mobos switched to a much more aggressive/fanless heatsync for the GPU:

IMO it'd be a lot cheaper/easier/more reliable to just swap to something like this, than an arduino monitoring solution. or if you're paranoid you could setup the arduino to cut power if temps rise above a certain point.

I'm not sure if the clamp attachment is the same between the old design and this one, but if it is that would make for a great drop-in solution. I know back in the day we also used to upgrade the thermal compound on these chips as well, the stock stuff is crap and given that there is internal temp monitoring it was proven to reduce temps a few degrees.

I suppose if you've got a hacked Xbox and access to both types of GPU cooler setups you could test and see which works better.

The Retail Xbox console also use an 80mm exhaust fan behind the CPU, while the Chihiro has a 60mm, though this seems to have really good CFM and run at high speed already. it could be argued that some ducting to draw air more directly over the CPU and GPU would be beneficial. On the Xbox the DVD and HDD trays acted like ducts for this purpose, while the Chihiro is a lot more open and has no such ducting for air-flow.
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Other common failure points are:
The Aerogel (memory) cap: this is the large cap on the bottom left, this is used to keep the clock running while power is off. They're prone to leaking and damaging the surrounding area. they can be removed without consequence, or replaced with a larger capacity unit, or battery.

The Memory Capacitors: these are the 3 (or 5 on older revision) large capacitors in front of the CPU, they're prone to failing and causing the mobo to FRAG. easy fix though.

back in the day a lot of people would heat sync the nVidia mobo chip, though I don't know how necessary it really was. to do so.


EDIT:
Sorry I didn't see obcd's post above when I started writing mine...

The bigger fanless heatsink used on xbox 1.1 - 1.6b mobo's (on the gpu) doesn't fit in a chihiro setup. The base board is 2 close to the main board and the heatsink doesn't fit between them.

I wonder if it's possible to just trim down a few of the prongs on this heat sync to clear. if memory serves only one edge of the GPU is overlapped by the chihiro daughter-board.

 

[winteriscoming]

The memory cap is a 1 farad goldcap. It usually starts to leak, and the stuff coming out is corrosive for the pcb tracks. The original xbox used it to keep it's clock going for a couple hours with the main voltage unplugged. It's on the left side of the pcb, close to the front border of it.

The bigger fanless heatsink used on xbox 1.1 - 1.6b mobo's (on the gpu) doesn't fit in a chihiro setup. The base board is 2 close to the main board and the heatsink doesn't fit between them.

On the power connector, there is a wire that is used to turn the power rails on and off (all 3 of them) On an ATX supply, you need to connect that to GND so that the supply turns on. The xbox and chihiro supply need a voltage on for the supply to turn on. I just don't know if it's 3V3 or 5V it needs. You have a standby voltage that remains present, even with the other voltages turned off. It could be used to power the arduino.

Thanks for the info! I'll have to explore the power question a little further.

 

[winteriscoming]

if you're paranoid you could setup the arduino to cut power if temps rise above a certain point.

I wonder how hard that would be. Would there be a way to get actual GPU temp to the Arduino? If measuring the ambient temperature near the GPU heatsink, what temperature is too high?

 

[Mitsurugi-w]

I suppose a small temp probe attached to the side of the GPU or directly in the heat sink would suffice.

 

[twistedsymphony]

a small temp probe attached to the side of the GPU or directly in the heat sink would suffice

this.

Personally I'd rather have temp monitoring than fan speed... I mean you could have the fan running at full speed and the GPU still cooking itself into oblivion.

 

[winteriscoming]

I think my fan pictured above was replaced at some point and probably not stock. I just opened up one of my xboxes with a fan on the GPU and the holes for the fan are farther out and I can see thread marks on my Chihiro's heat sink that makes me think it had a different fan installed at some point. The holes look to be spaced more for a 50x40mm fan where the mounting points allow the 40x40mm body to recess down into the slot and sit right up against the heat sink.

Personally I'd rather have temp monitoring than fan speed... I mean you could have the fan running at full speed and the GPU still cooking itself into oblivion.

I suppose this is true. I wonder what would be considered ideal temp or what temp would be considered approaching out of spec and require a shutdown?

I suppose a small temp probe attached to the side of the GPU or directly in the heat sink would suffice.

Would it be safe to assume that the external temperature would likely be lower than the actual GPU? If that specific info isn't available, assuming you're starting with a good Chihiro, If installing a probe like this, I guess I could start by taking readings over the course of an hour and get an average and high over that time. The assumption being that anything higher than the high during that period might be dangerous and merit a shutdown.

 

[twistedsymphony]

I suppose this is true. I wonder what would be considered ideal temp or what temp would be considered approaching out of spec and require a shutdown?

you don't really need a spec. just measure the temp under load with ideal ambient conditions add 10 or 15 degrees to set your shut down point and bobs your uncle.

there's going to be variation depending on where you place your probe so you're better off doing it this way anyway.

 

[obcd]

The chihiro case fan is always running at maximum speed. The xbox case fan is running at reduced speed to be more quiet. In an arcade, you don't hear the noisy fan under your seat. In your living room, it's a different story. The GPU heats more when it has to work much. In a chihiro, this is almost always the case as it keeps showing the demo of it's game. On a xbox, it's usually not rendering a game for 12 hours a day.
On ther xbox, most dashboards had an automatic temperature control. Not sure if it's the dashboard controlling the fan speed or if the pic processor has some buildin routines to speedup the fan when the temperature becomes 2 high. Only the case fan is controlled, the gpu fan always runs at full speed.

I am under the impression that the smaller heatsink (with working fan) provides a better cooling than the bigger heatsink. They likely started to mount the bigger heatsink because it's cheaper, more reliable and less noisy.
I am not convinced it would be a better solution for a chihiro. Maybe someone can prove I am wrong.

 

[twistedsymphony]

I am under the impression that the smaller heatsink (with working fan) provides a better cooling than the bigger heatsink. They likely started to mount the bigger heatsink because it's cheaper, more reliable and less noisy.
I am not convinced it would be a better solution for a chihiro. Maybe someone can prove I am wrong.

I don't know that it'd be cheaper from a manufacturing perspective, while the fan is more complex, aluminum is fairly expensive.

I don't know which is better at cooling, but i do know which is better at not dying testing which is better at cooling shouldn't be a problem... I need to dig some old Xboxes out of storage at some point.. I'm open to suggestions of easily repeatable, graphically intensive game sections to test temps under load.

Even if the Xbox heat-sync isn't a good option It'd be worth researching alternative heat-syncs... I'd rather have one fewer points of failure is possible.

 

[Gakman]

Good topic.
So, if we need a list for now:
_ remove memory cap
_ change fan
_ optional : change CPU caps

 

[jugu]

Good topic.
So, if we need a list for now:
_ remove memory cap
_ change fan
_ optional : change CPU caps

Should that be "replace memory cap" instead of remove?

 

[obcd]

remove or replace. It's not needed on a chihiro.

 

[winteriscoming]

I checked both of my Xboxes I have on hand. They're both older models with GPU fans, so I don't have a larger heat sink to measure for fit in the Chihiro.

My 2nd Chihiro has what I assume is the stock fan and resembles the ones in the Xboxes.

Whoever previously serviced my 2nd Chihiro conveniently removed the memory cap, but decided the screws that hold in the PCB above the Xbox board weren't needed...

 

[jugu]

remove or replace. It's not needed on a chihiro.

Ah good to know.

Thank you.

 

[obcd]

The newer heatsink that doesn't need a fan (on xbox) is 25 mm high. It might fit in a chihiro setup.
I tried it with the 10mm high blower on top of it which didn't fit in.
The clamp fixation is identical. You can mount the bigger heatsink in the place of the smaller one with the fan. The small heatsink uses a flat metal clamp (to leave room for the fan) The bigger one uses a plastic one (which is more fragile after all those years.) My apologies for the misinformation that the bigger heatsink wouldn't fit. At the moment, it needs testing.

 

[winteriscoming]

I'm picking up one of the larger heatsinks. I'm thinking a fan could be mounted to the side for overkill.

Looking over the Chihiro, it looks like there's ample room for a 2nd case fan on the side with all the vent holes. You could likely get a fan to line up with some of the holes to secure it in place. I also noticed the fan header that the Xbox uses for the case fan is unused on the Chihiro. I wonder if that header gets power. Chihiro's case fan looks to get wired straight into the 12V from the power wires coming into the mobo, so that would potentially be an option for a 2nd case fan, too.