New PSU - EDIT - sorted! Thanks all

Diggsy

Diggsy

Diggsy

Soldato
Joined
31 Aug 2007
Posts
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As per title, I’ve just today received a brand new Phanteks AMP 750w PSU.

Installed it all correctly, switched on…won’t boot! Starts to boot, no beep, then just seems to be going nowhere. Nothing on the screen, no beeping.

All fans spinning and appears fine otherwise but just won’t boot.

Have checked, double and triple checked all connections and no difference. Changed power cable just in case but nope, nothing.

Have just plugged in an old cheap unit I had in the garage and the PC is up and running, so clearly it’s not a fault with the system.

Is it a dud, or have I missed something obvious?

My system is older and certainly not power hungry:

Gigabyte Z77X-D3H
Intel i5 3570k at default
16gb Ram (4x4gb)
GTX970
1TB Crucial MX500
X-Fi sound card
 
Yeah, sounds like it is broken. If you feel around the edge of the ATX 20/24 pin is it deffo fully seated? They can be awkward sometimes, especially around the 4 pins that break off on the 24 pin.
 
Thanks for the reply. Yes I checked and double checked all the connections. Actually removed them all from both ends and reconnected to be certain.

As you say, that main ATX one is a tricky one, as is the 8 pin PCI-E one for the graphics card, so I really made sure to take my time with those.

Sounding like it’s a dud unfortunately…
 
You checked the RAM sticks for any faults bud, its always worth trying these simple steps even if your sure it's not them
 
Thanks for the suggestion. Haven’t done that, but suppose a minimal boot effort might be worth it just to see / maybe prove the point. Does seem odd though that it boots fine with the other PSU, and never had an issue with my previous one until it stopped working.

I actually have another identical board with different memory in it. Might try that
 
I read a while back - and I'm scraping the edges here so hopefully I've got this right - that some systems were having problems with PSUs where the currrent on one of the less important rails wasn't enough to trigger system start. If you could get it running it was fine on restart etc, but cold boot just wouldn't happen. I'll see if I can find anything on it. I hope I'm remembering that right

a quick google and I can't find it. Probably best disregard. I need to start bookmarking these things.

Out of interest can you give details of the other PSU so we can compare specs?
 
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So the Phanteks unit has a high transient drift on the 3.3V rail https://www.tomshardware.com/reviews/phanteks-amp-series-750w-power-supply/4. Apparently this matters for RAM, so could you be getting a spike under/over that is interfering with boot?

Also not sure when your mobo dates to but the same TH review notes in the conclusion:
The recent additions in the ATX spec, which apply from 2020, require among others for higher than 70% efficiency at 2%, of the PSU's max-rated-capacity, load, and for a power-ok delay signal within 100-150ms. The AMP 750W doesn't meet those requirements, so at some point, Phanteks should consider upgrading the platform to be fully compatible with the newest ATX spec.
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If your mobo needs that could it be signal delay?
 
VaderDSL said:
Daft question, you aren’t re using cables from the old PSU are you?
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Good point, that could certainly cause issues. It's why when i changed my psu recently i went same brand, same range, just more W so i could keep the cabling! (I love fully modular supplies :) )
 
ik9000 said:
Good point, that could certainly cause issues. It's why when i changed my psu recently i went same brand, same range, just more W so i could keep the cabling! (I love fully modular supplies :) )
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There’s no daft questions I can assure you - nope, all the new cables.
 
ik9000 said:
So the Phanteks unit has a high transient drift on the 3.3V rail https://www.tomshardware.com/reviews/phanteks-amp-series-750w-power-supply/4. Apparently this matters for RAM, so could you be getting a spike under/over that is interfering with boot?

Also not sure when your mobo dates to but the same TH review notes in the conclusion:

If your mobo needs that could it be signal delay?
Click to expand...
Thanks for your reply and that info. Don’t think that would affect me…my system is too old for that to matter, as far as I can tell anyway! Good idea though.
 
Okay, so it may be an issue with my current setup. Have no screen connected yet, about to do that of course, but it beeped as expected in a normal post and appears to be running normally from what I can tell. Going to connect a screen and Kb and see what happens…
 
Well, all I can say is thanks guys! Without your advice I’d probably just have assumed it was faulty and sent it back…

Have the other system sitting at the Windows Home Screen right now. Booted up just fine.

So…now to work out which one of the old system components is to blame. RAM seems to be a good starting point, or perhaps I’ll just removed that board and run with this one as it’s effectively the same anyway!
 
Just thought I’d give one more update to this. System all swapped over. Didn’t bother to further troubleshoot the old board and RAM, but I suspect the latter was just being picky.

The alternative system (identical, with different RAM) is up and running perfectly.

I must say the PSU is completely silent. I have the hybrid switch on, so the fan doesn’t even come on until it gets to a certain load. I’ve not pushed the system yet but I’m impressed so far.

Edit - have done a run of Prime95 and another of Heaven and the noise levels are excellent. In fact, it’s actually reduced what I felt was perhaps coil whine from the GFX card to inaudible levels now. Win win!

Thanks again for everyone’s advice and input.
 
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