Computer shuts down under heavy load

SgtSiff

SgtSiff

SgtSiff

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Joined
27 May 2012
Posts
5
Hi guys, this is my current set-up:

i7-3770s
Samsung 830 128GB
H77m-itx
8GB samsung green ram
Slim slot loading blu-ray drive
HD-Plex H3.SODD
120w PicoPSU/ 300W SFX PSU

I'm having problems with my computer shutting down under heavy load (converting videos, prime95 etc) but i'm not really sure why.

At first I thought it was a heat issue but running real temp with CPU usage at 99-100% shows temps of around 80c which is fine.

Next I thought it was the 120w Pico psu not giving enough juice so I connected a 300w atx psu, the computer ran fine all the way through the prime95 tests without shutting down.

Great I thought, but before I took the plunge on a more powerful pico psu I decided to buy a power meter to see exactly what size supply I would need, (here is the strange part) with the cpu at 99-100%, a blu-ray being ripped and copying a big file to the ssd from an external drive, the system only pulled ~80W.

The only things I can think of are:

-The pico psu has a 20 pin mobo connector whilst the atx psu has a full 24 (I didn't think this would matter, i thought the extra 4 were for the pci-e bus)

-The pico psu didn't come with the seperate 4 pin connector (auxillary?) So i used a molex to auxillary connector such as this one : No hotlinking! I understand this auxillary is to provide extra power for the CPU, but if that is the problem, why is it a couple of minutes of 100% cpu usage before it shuts down?

-I've been shafted and the 120w pico psu isn't 120w. I can't see any markings on it to identify it as 120w but I bought it from a respectable vendor.
 
120w seems pretty tight for a 3770S.

These PSUs don't really have that much amps on the 12v rail, and since you're using a molex adapter for the 4 pin, when you stress the CPU this also stresses the PSU and causes it to crash. That 4 pin connection is direct power to the CPU itself.
 
Thanks, so even though the system is only pulling 80w, it is pulling more current than is available on one rail?

Do you think a 160w pico psu will give the extra oomph required?
 
Most of the juice a CPU's going to pull is 12V I believe. Assuming you have a modern Mini Box 120W Version, that only supplies 6A on a 12V rail only giving you 72W on the 12V line, not really enough to meet the TDP of your processor given as an indicator if you also account fans, a little on the chipset and HDD (if it's 3.5") as these all suck on your 12V further.

What amps does your AC-DC Brick put out? This also as they dictates your Picos ultimate power.

My suggestion is get a 160W pico and matching brick or even a PW-200-M with a 192W 12V supply brick as this had a much beefier 12V.
 
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does it actually shutdown or does it BSOD then reboot or just suddenly power off?

If it powers off without even attempting to shutdown probably a PSU issue/not enough juice

If it BSOD's then RAM/Driver/Overclock problem

If it suddenly initiates a proper windows shutdown for no reason then check event log there should be a reason in there
 
stueng - Just suddenly shuts down

There are no fans but I guess it must be pushing the 12v rail a bit too much like you said. The power brick is rated at 120w.

Being as the system is only puling 80w, I should be find with the 120w external brick and a 160w pico psu?
 
The 120w should be fine, easy enough and then some.

I can pull 120w (in fact slightly over) off my cheap £16 120w pico I bought off ebay.

I suspect the pico is either slightly faulty or you have a poor quality power brick.
 
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