On Tue, Dec 30, 2014 at 01:58:57PM -0500, ted leslie wrote:

​Some new video cards require​ PS 4-6-8 prong plugs right to card from PS. So if your PS doesn't have those, you are SOL. As well, if it doesn't need those, the cards, especially recent ones have power saving features, i.e. turn up their performance as needed, so power draw can flux. Only way to tell is add the max draw watts from everything, including max draws from drive start up surges, etc, and leave a bit of room as well. 300w seems pretty low.

Some cards do come with adapters to convert 4 pin drive power connectors to the PCIe power connectors. So you might not be out of luck in all cases. -- Len Sorensen

On 12/30/2014 03:43 PM, Lennart Sorensen wrote:

...

I know this really isn't about Linux per se, but I thought I would ask this question here any how. I have a computer wit a 300W PSU. It currently has an onboard video chip, which I would like to replace with a video card. Now, the video card specs mention needing a 300W PSU. My question is: Would that 300W requirement be a minimum, or what the card would need to work full-on? Thanks, Assuming it is a proper 300W power supply (and not some cheap pretend

On Tue, Dec 30, 2014 at 06:14:54PM +0000, DAVID CHIPMAN wrote: power supply), then it is probably OK. The video card recommendations are not for how much the card needs, but for what they expect a typical system with that card to need.

So it is probably OK.

Of course if you have an old system with one of those 150W Pentium 4 chips, then maybe not. :)

If you have a hardware nerd, take them along when you buy power supplies. The difference in the contents of one of those shiney little cases is amazing, even with the same part number on the outside. --dave -- David Collier-Brown, | Always do right. This will gratify System Programmer and Author | some people and astonish the rest davecb@spamcop.net | -- Mark Twain

On Thu, Jan 01, 2015 at 12:18:35PM -0500, Anthony de Boer wrote:

If memory isn't completely failing me I think I recall Henry Spencer once saying to pick them both up and buy the heavier one!

That was true before we got switching power supplies. These days it is way more complicated than that.

(Bigger heatsinks and beefier components certainly don't hurt. Granted, there are a few other factors, including efficiency if you're paying for your own power these days and it's for a 24/7 box.)

Wish it was that simple. These days there are questions of using the right number of caps for filterting and in the right places and the right types, and how well distributed the voltage rails are in terms of current at each voltage. -- Len Sorensen

| From: Kevin Cozens <kevin@ve3syb.ca> | Any spec for a video card as to power supply wattage would be a minimum. Not in my (limited) experience. I have bought cards that wanted to specify how big my system's power supply was because the actual required arithmetic is too hard for customers. They just guessed at what the rest of my system would require and left a margin for error. The real specs are a little tricky in theory (I don't actually know what things are like now). The power supply supplies various voltages, each with its own current limit. Each voltage is provided on one or more "rails", each with its own limit. But sometimes a maximum draw on one reduces the limit on another rail. You need a power supply that has enough oomph on each rail. So you want a requirement specified for each voltage. And generally you don't know how much power the rest of your system uses in aggregate. Usually when you build your own system you buy more power supply capactiy than you need. It doesn't cost too much more and you don't really know what's needed. I imagine that common garden variety computers from big manufacturers tend to size their power supplies with smaller margins.

On 01/06/15 08:14 PM, David Thornton <northdot9@gmail.com> wrote:

Some bioses (bioii?) will tell you about consumption, if that's any help.

I'd go with the Italian 'biosi'.

The software package lm_sensors might be able to help you see what data is made available but YMMV as there is no widespread "standard" for access to power consumption data as far as I know.

Expensive servers have polished aps for acessing that sort of data....

ha! I googled "measuring pci card power consumption" and the first hit was

"How We Measure Graphics Card Power Consumption ..." http://www.tomshardware.com/reviews/graphics-card-performance-benchmarks,378...

Very sexeh setup.

David

david

On Tue, Jan 6, 2015 at 2:18 AM, D. Hugh Redelmeier <hugh@mimosa.com> wrote:

...

| From: Kevin Cozens <kevin@ve3syb.ca>

| Any spec for a video card as to power supply wattage would be a minimum.

Not in my (limited) experience. I have bought cards that wanted to

specify how big my system's power supply was because the actual

required arithmetic is too hard for customers. They just guessed at

what the rest of my system would require and left a margin for error.

The real specs are a little tricky in theory (I don't actually know

what things are like now). The power supply supplies various

voltages, each with its own current limit. Each voltage is provided

on one or more "rails", each with its own limit. But sometimes a

maximum draw on one reduces the limit on another rail.

You need a power supply that has enough oomph on each rail. So you

want a requirement specified for each voltage.

And generally you don't know how much power the rest of your system

uses in aggregate.

Usually when you build your own system you buy more power supply

capactiy than you need. It doesn't cost too much more and you don't

really know what's needed.

I imagine that common garden variety computers from big manufacturers

tend to size their power supplies with smaller margins.

---

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