low watts but high amps. what is more important?

[luismenendez]

Hi guys,

I got a PSU with low watts but most of them on the 12v rails (2x12v rails, each one 16a).

Do you think it could handle an I7 4770 and a GTX 1050i?

According to many reviewers and Nvidia specs the card tops at 75w and around 4a so doesn't need a PCIe connector.

Rest of the system is an SSD 168GB, HDD 500GB and Creative XFI on a apparently simple Lenovo mobo with SATA3 and 2x8GB PC3 ram.

Funny enough the PSU has only 15W and 2.5a for 5v but doesn't have any ratings for a 3.3v rail so I guess the system doesn't need it!

cheers

 

[chrcoluk]

yeah that should be fine providing not sharing one rail, if the psu documentation tells you which rail the cpu is on, put the gpu on the other rail.

My old psu was 40A on 12v single rail which is 480watts, so your combined 32A is about 395W.

 

[EsaT]

Funny enough the PSU has only 15W and 2.5a for 5v but doesn't have any ratings for a 3.3v rail so I guess the system doesn't need it!

What's the model of that PSU?
Or better yet take picture of spec label.

5V standby is quite often 2.5A, but actual main 5V rail should be 10A.
Also 3.3V isn't some voluntary rail, but necessary for ATX PCs.

So smells heavily like some non-standard proprietary mess.

so your combined 32A is about 395W.

You never sum together current limiter values.
Just like power line coming into your house can't actually carry summed amperage of all fuses.

 

[luismenendez]

It is a customised Lenovo mobo with a customised LITEON PSU which has only 270W on the 12v rails so I was surprised to see 2x12v rails (one is for the CPU and the other for the mobo as per PSU details) with 16a each for a total of 32a

The mobo 12v connectors from the PSU are 4 pin and 14 pin!!

So do you think will handle a GFX 1050Ti small factor which only draws the power from the PCIE slot?

Cheers

 

[chrcoluk]

Can you clarify more esat?

I have never been a fan of multi rail psu's anyway but are you saying a single rail 12V psu with 395w may handle 395w but a dual rail psu with combined 395w on both rails may not handle full load on both its rails?

I would assume it be fine providing the total capacity of the psu is higher than the combined value, I dont think I have ever seen a psu with 12v capacity spec'd higher than the psu itself.

I see now luis just posted and it does indeed seem his psu has capacity lower than the 12v rails combined, so I guess it is possible. First time I seen such a psu but I guess is a first time for everything.

 

[EsaT]

It is a customised Lenovo mobo with a customised LITEON PSU which has only 270W on the 12v rails so I was surprised to see 2x12v rails (one is for the CPU and the other for the mobo as per PSU details) with 16a each for a total of 32a

The mobo 12v connectors from the PSU are 4 pin and 14 pin!!

So do you think will handle a GFX 1050Ti small factor which only draws the power from the PCIE slot?

That's proprietary mess.
And there's certainly 3.3V step down switcher on mobo, because PCIe requires that.

While that PSU certainly isn't going to break bank in quality, it should be well enough for those parts unless it's worn out.

 

[EsaT]

I see now luis just posted and it does indeed seem his psu has capacity lower than the 12v rails combined, so I guess it is possible. First time I seen such a psu but I guess is a first time for everything.

It has always been that way since marketroids started whole "multi-rail" shenanigan.
Simply because if tightly distributed, there wouldn't be any real way to use all output without completely custom built for that PSU hardware.
There's simply way too much variation from PC to PC in what parts draw the most power.

And of course 2x16A looks better in marketing than honest 22.5A, fooling uneducated people.

 

[chrcoluk]

yeah the marketed reason was always to "isolate rail failures from each other".

Glad the market has now moved back to single rail dominance.