How many watts do I need?

Derek · Post by **Derek** » Fri Apr 06, 2007 12:34 pm

I'm thinking of getting a better graphics card, a nvidia 7600gt to be precise, but no matter how much googling I do I can't seem to get a definitive answer to a question.

So, here goes..

I have an intel 6300 core 2 duo which I believe takes about 65-95 watts, a 7300se graphics card which uses I don't know what watts.

1 gig 533 memory, 2 hard disks, 1 dvd-rewriter and a motherboard all being driven off of a 250watt power supply.

The question is does anyone know if I can just change the graphics card and expect it to work or will I need a better power supply.

From what I can find on the web it seems like the 7600gt needs about 67watts but I don't know it that is right or not.

Anyone else using a similar setup to this with a reasonable graphics card and a low power supply?

Tipperton · Post by **Tipperton** » Fri Apr 06, 2007 12:40 pm

Here's a PC power supply calculator that might help you:

http://extreme.outervision.com/psucalculator.jsp

I also found this on Leadtek's web site about their 7600 GT card (I suspect any other 7600 GT card will have the same requirements):

A minimum recommended 300W system power supply required. For two PX7600 GT running in SLI configurations, a minimum 400W system power supply (with 12V rating of 22A) is recommended.

Derek · Post by **Derek** » Fri Apr 06, 2007 1:01 pm

Thanks for the info.

Here's a link to a page with wattage consumption on it.
http://www.vr-zone.com/?i=3335&s=8

I've read on a few pages about manufacturers saying you need 300 or 400 or even 500 watt supplies, apparently this is just them safe guarding against unreliable supplies or users not actually knowing their requirements.

On paper at least it looks like I should be able to use this card without changing the power supply.

Will give a go in a month or so anyway, what's the worst that can happen!!

Derek · Post by **Derek** » Fri Apr 06, 2007 1:21 pm

@Tipperton, ran the tester at your link.

Put in everything I have but changed the graphics card to the 7600gt, came back at 248 watts.

Just a bit tight I think, unless I take out a pci card or two.

Joakim Christiansen · Post by **Joakim Christiansen** » Fri Apr 06, 2007 2:58 pm

I think 250watt might be too little, I would at least have one with 400

thefool · Post by **thefool** » Fri Apr 06, 2007 3:36 pm

Just buy a huge powersupply. It won't use more power but it has the ability to give more (eh if it gives more then it will of course use more power!)

Bonne_den_kule · Post by **Bonne_den_kule** » Fri Apr 06, 2007 4:14 pm

350W is enough.

thefool · Post by **thefool** » Fri Apr 06, 2007 4:18 pm

Bonne_den_kule wrote:350W is enough.

Yes, but a 300W was too little for me. So there is no harm in going 400 JIC
You don't know how much stuff he will put on it later on.

GeoTrail · Post by **GeoTrail** » Fri Apr 06, 2007 8:05 pm

I have sold my old PC, replaced it with a new laptop.
But my old system had a 7900 GTX card and I used a 500W PSU without any problems. Although, the GTX cards uses A lot more power then the card you mentioned.

KarLKoX · Post by **KarLKoX** » Fri Apr 06, 2007 8:14 pm

This is not only a problem of watts but of output : i strongly suggest a good psu with a good output of 350w against a 550w poor ineffective psu : Enermax, Antec, Silverstone, Hiper are good choices.

Derek · Post by **Derek** » Fri Apr 06, 2007 8:36 pm

Thanks guys, as you say it is not only watts to consider but amps as well.

Looking more and more like I will have to buy another power supply, never mind, I was expecting to pay around £100 for the card and it looks like I can get one for £70 so the power supply is more or less payed for anyway.

GeoTrail · Post by **GeoTrail** » Fri Apr 06, 2007 9:54 pm

That's true.
Here's the PSU I had http://www.nexustek.nl/nx5000_real_sile ... supply.htm

Derek · Post by **Derek** » Fri Apr 06, 2007 10:12 pm

Thanks, will have a look.

The other problem I have is that my computer is a Packard Bell and so some of the parts may or may not be non-standard, I read somewhere that the power supply may be one of the non-standard parts, will have to dig a big deeper and find out for sure.

Tipperton · Post by **Tipperton** » Fri Apr 06, 2007 11:18 pm

KarLKoX wrote:This is not only a problem of watts but of output

That's true, watts is a simple way to measure power supplies but what you really need to watch is how much current is available on each of the rails, especially if you get a power supply that has multiple +12V rails as most SLI or CrossFire rated power supplies do.

I learned my lesson about power supply quality several years ago when I built this machine. I used an inexpensive ($30) 500W power supply and after a while had strange lock-up and resetting problems. I saw a comment by someone that said:

It always surprises me that people will spend lots of money on top-of-the-line parts for their computer and power it with an el-cheapo power supply

So I bought a high quality ($100) 430W power supply and all the lock-up and resetting problems disappeared.

Another guy said:

One good way to judge power supplies is to heft them in your hands, the heavier one is more than likely the better one

Don't know how true that is but I do know that the high-quality power supply I bought was at least three times heavier than the el-cheapo it replaced.

This is the power supply I have now: http://www.newegg.com/Product/Product.a ... 6817103939

One of the things I really like about it is that the only cables permanently attached are for the motherboard. That way you only attach what you need for your drives, video boards, fans, etc. and don't end up with a bunch of un-needed cables cluttering up the inside of the computer.

Derek · Post by **Derek** » Sat Apr 07, 2007 9:48 am

Apparantly the supply I have also have a connector for the speakers but seeing as mine are externally powered that doesn't matter.

Packard Bell wrote: Although ATX power supplies conform to various specification guidelines, there is not, unfortunately, a standard ATX power supply. To find a suitable replacement power supply for your machine, we would recommend that you have the following information to hand when making your purchase:

- You will require a PSU with a 24-pin ATX connector, SATA power connectors, and a 4-pin 12V motherboard connector
- Make a note of the wattage of your existing PSU
- Make a note of the external dimensions of your existing power supply
- Be aware that your PSU has a power connector for speakers. Most PSUs do not have this, so you may need to purchase a separate power supply for your speakers.