trying to understand power supplies with SLI

[DrDuke]

I am trying to wrap my head around the numbers and different models.

According to the faq here, ( which is awesome btw jiggamanjb ) you want a minum of +12V@34A.

and according to this site's power supply calculator, with my current setup plus two 7900gs calculates at 350watts

my xfx 7900gs's also use the 4pin style power connectors, opposed to the pci-e 6pin - I don't know how that effects the equation...

I am not opposed to spending money and doing things the right way, but I would like to know why I couldn't just use the Antec true power 2.0 480watt psu I have now? According to antec, which has a reputation for being honest on their ratings it meets my needs as far as I can tell.

right?

 

[jivetrky]

Your PSU will probably handle your SLI 7900GS's just fine.

I'm not sure how much CPU/GPU overclocking it would handle....but with only mild overclocks, it should be ok.

But if you look to upgrade in the future you would certainly need a better PSU (be it SLI 7900GTX's, or without a doubt for a single 8800 series card)


EDIT: and BTW, I'd say that if you ever do upgrade from that setup, moving to current gen cards would be the only smart option. I don't think a move to 2x 7900GTX's would be worth the trouble or money to upgrade. Since a single 8800GTX can beat a pair of 7900GTX's

 

[DrDuke]

Your PSU will probably handle your SLI 7900GS's just fine.
...

I don't think a move to 2x 7900GTX's would be worth the trouble or money to upgrade. Since a single 8800GTX can beat a pair of 7900GTX's

Thanks for the input, I just wanted to get this computer running and waiting a week or so for a new psu.... sigh.. Good to know it should handle it for a while.

For the record, I think 7900gtx's in SLI will out preform a single 8800gtx. However your are entirely correct in stating it would be a stupid upgrade value/performance wise.

I hope these 7900's will keep me happy until the 8800's have a similar price break next year....

If these hardware companies keep up with the crazy power demands, I will have to put in another 220v line to my house like I did for my mig welder.

On a side note, has anyone dared to look at their complete order history on newegg and add up how much they have spent there. SCARY! I notice my upgrades all fall on the similar price annually or bi-annually.

 

[jivetrky]

Thanks for the input, I just wanted to get this computer running and waiting a week or so for a new psu.... sigh.. Good to know it should handle it for a while.

For the record, I think 7900gtx's in SLI will out preform a single 8800gtx. However your are entirely correct in stating it would be a stupid upgrade value/performance wise.

I hope these 7900's will keep me happy until the 8800's have a similar price break next year....

If these hardware companies keep up with the crazy power demands, I will have to put in another 220v line to my house like I did for my mig welder.

On a side note, has anyone dared to look at their complete order history on newegg and add up how much they have spent there. SCARY! I notice my upgrades all fall on the similar price annually or bi-annually.

Actually that link you provided shows the single 8800GTX outperforming SLI 7900GTX's

 

[MVC]

On a side note, has anyone dared to look at their complete order history on newegg and add up how much they have spent there. SCARY! I notice my upgrades all fall on the similar price annually or bi-annually.

I haven't looked at a COMPLETE history, but I see the annual numbers every year when I have my taxes prepared (I do consulting on the side and my computer equipment is mostly a business expense ) A little bit here and a little bit there soon adds up to real money! I know I couldn't afford what I'm spending if I couldn't write it off as a business expense.

 

[DrDuke]

Actually that link you provided shows the single 8800GTX outperforming SLI 7900GTX's

Whooops.... I mixed that all up in my head. I feel a little sheepish that I went to look for that article and didn't bother to check and see if my memory on the article was correct. I guess this is the second mistake I have ever made I spent way too much time today looking at power supplies today... yeah thats the ticket.

A single GeForce 8800 GTX is more powerful overall than a 7900 GTX SLI configuration

 

[jivetrky]

It's ok....I have done that severeal times.....sometimes the graphs and numbers get a little jumbled

 

[Section8]

Thanks for the input, I just wanted to get this computer running and waiting a week or so for a new psu.... sigh.. Good to know it should handle it for a while.

For the record, I think 7900gtx's in SLI will out preform a single 8800gtx. However your are entirely correct in stating it would be a stupid upgrade value/performance wise.

I hope these 7900's will keep me happy until the 8800's have a similar price break next year....

If these hardware companies keep up with the crazy power demands, I will have to put in another 220v line to my house like I did for my mig welder.

On a side note, has anyone dared to look at their complete order history on newegg and add up how much they have spent there. SCARY! I notice my upgrades all fall on the similar price annually or bi-annually.

I had 2 7900 GTX's that were factory OC'd from XFX and they were about 20% slower than 1 of my 8800GTX''s.

 

[darkcow]

yea, that psu you have now is perfect for the job. but wait untill you get your 8800gtx's and get your psu with it. save on shipping

 

[jiggamanjb]

yea, that psu you have now is perfect for the job. but wait untill you get your 8800gtx's and get your psu with it. save on shipping

ditto

ps - thanks for the props DrDuke!