x2 Swiftech MCP 355's dead at once?

[StAndrew]

Bought two separate Swiftech MCP 355's and they were running without any issue for the last 6 months. I have heatsyncs (not swiftechs) that mount directly on the PCB and I have a 120mm fan right under it blowing. I've also ran the pumps at around %60 in speedfan.

Today I turned on the computer and neither pumps are working. I checked the voltage at the fan headers and the molex connectors and they are all reading 12v. I checked the resistance on the pump connector and they both read ~14kOhms which is what they read when I first installed them (checked to help future troubleshooting).

I'm a bit baffled and really don't know where to go from here without tearing down the loop and opening the pumps.

[madmaxx]

Strange, 2nd hand pumps? How are the pins on the pump side molex? I've seen them lose tension and break contact before.

[StAndrew]

No, brand new. Loop is tore down right now for cleaning, we'll have to troubleshoot next week.

I think it might be the fan headers in the motherboard not making good contact as one of the pumps had an issue with this early on. But its mighty strange for both to stop...

[madmaxx]

Worst case you still have warranty, right? IIRC the 355s have the upgraded PCB so they should be more tolerant, let us know...

Can you try a fan on those headers to confirm they are live? They are pins so if there is power, there is power and the problem is most likely the molex connector on the pump leads.

[StAndrew]

I do have the warranty, yes. They are both new.

I got the loop back together and now one comes on reliably but the other, while sometimes comes on just fine, it sometimes is delayed or wont come on at all.

At one time, I found that messing with the PWM header got it to come on so I thought maybe its not making good contact. However, when I used a probe in the back of the connector (pump side), it is getting good contact and good voltage. It just doesn't want to come on all the time. Possibly something wrong with the PWM controller?

[StAndrew]

Sorry, belay my last.

So here is the issue. When I start it up after a prolonged shut down, the pumps click. I can't hear it but can feel it. If I start tapping them, they come on...

[madmaxx]

Sounds like RMA time.

[StAndrew]

Sounds like RMA time.

So I can't find anything if I search for MCP but if I search this problem using DDC, its not uncommon with the traditional fixes either being an air bubble in the pump or a water change needed

I just did a water change when I installed these pumps so I'm guessing an air bubble...

The issue now is that when I accidently boiled the water in my CPU block about a week ago, which I think may have caused the acrylic on my CPU block to crack and I've been getting a small water leak down my motherboard and GPU's. I'm in the process of cleaning that up and have a new CPU block on the way, courtesy of Swiftech (their RMA is great btw).

[madmaxx]

I highly doubt cavitation is the issue, could be wrong. Swiftech warranty/RMA is good if you're in the US, from my experiences.