dont wanna buy a new psu for new vid card

skiplar316

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heres one for the modders :D

hey guys i want to get a 8800 gts for my system currently i know that i do not have enough power for it but i dont want to buy a new psu i have 3 perfectly good 250 watt psu's laying around useless to me. what i would like to do is use a psu to power the gfx card only.

i know i sound like a fuckin tight wad but hey i might as well use it :oops:

my questions are

1.i know that vid cards draw power from the system bus but how much if any (since the card requires seperate power connections) is drawn from the system?

2 is there enough power in that single psu to power the gfx card by itself?

thx guys for any help you can offer :)
 

jetfx

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they can take up to 75watts from the pcie-e top, wee need to know ur system specs man to help you, what brand and how many amps does tht 250watts psu can handle, and do they have pcie conectors?? whats ur main psu.
system specs, system specs
 

skiplar316

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ok lets see
my system specs

350 watt psu
pentium D 820 2.8
seagate 250 gig HDD serial ata
asua p5lp mobo
dvd rw drive
i currently got a crappy bfg 5500 oc gfx card that i riped out of an older comp installed
thats about it for the system

the additional psu i got has a 14A output on the 12v rail
 

jetfx

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u need at least 30amps in the combined v12 rails to make ur rig work, so it would mean no, u canot use tht main psu fo a system like that.
i recommend u to change ur psu for somthing better pick a good brand read PSU 101 to see what you need just stay above 30amps, using ur main psu combined with the 250 u already have could work but its risky since u didnt post the brand of ur psu's im gonna guess they are bad,
 

3lfk1ng

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Hate to say it, but I'll keep it simple:

If you want an 8800 gts, you have absolutely no choice but to purchase a new power-supply.

Best of luck.
 

skiplar316

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if i combined the 350 psu and the 250 psu i have over 30 amps on the 12v rails but i cannot see the vid card itself using 30 amps of power

i guess what im looking for is someone that actually knows. how much current the card draws from the bus, and how much current it draws from the pci-e power connector.

or if someone can direct me to a link that has that sort of info

i thank you guys for your help. but i think that it is premature to believe that it wont work. good actuall data will help me make the determination on wether or not to try it out.
 

TonyStark

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i guess what im looking for is someone that actually knows. how much current the card draws from the bus, and how much current it draws from the pci-e power connector.
The vid-card will use:

* 75 W from PCI-E slot
* 75 W from 6-pin PCI-e connector x 2 connectors = 150 W
= 225 W max

Divide that by 12 volts and you get about 18.75 Amps MAX current draw.


Now, if you use multiple PSU's, you will need all of them to be connected to the motherboard. I read a guide on another forum about connecting multiple PSU's to a mobo, I'll try and dig it up for you.

EDIT: I can't find the original guide mentioned above. However, you could also try something like this: Multiple Power Supply Guide
 

sirheck

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heres one for the modders :D

hey guys i want to get a 8800 gts for my system currently i know that i do not have enough power for it but i dont want to buy a new psu i have 3 perfectly good 250 watt psu's laying around useless to me. what i would like to do is use a psu to power the gfx card only.

i know i sound like a ****** tight wad but hey i might as well use it :oops:

my questions are

1.i know that vid cards draw power from the system bus but how much if any (since the card requires seperate power connections) is drawn from the system?

2 is there enough power in that single psu to power the gfx card by itself?

thx guys for any help you can offer :)

too bad. you have to buy a new psu.


but then agian dont and fry something. :roll:
 

skiplar316

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i guess what im looking for is someone that actually knows. how much current the card draws from the bus, and how much current it draws from the pci-e power connector.
The vid-card will use:

* 75 W from PCI-E slot
* 75 W from 6-pin PCI-e connector x 2 connectors = 150 W
= 225 W max

Divide that by 12 volts and you get about 18.75 Amps MAX current draw.


Now, if you use multiple PSU's, you will need all of them to be connected to the motherboard. I read a guide on another forum about connecting multiple PSU's to a mobo, I'll try and dig it up for you.

EDIT: I can't find the original guide mentioned above. However, you could also try something like this: Multiple Power Supply Guide

hey tony thx for the info man :) and the link is very usefull im very suprized that a guide like that doesnt exist on this site

where may i ask did you get the power consumption numbers for the vid card? after many hours on google i couldnt find that info. also the 8800 gts's i have been looking at on newegg they all seem to have only 1 6 pin connector on the card

if they have 2 connectors i could possibly use 2 of the 3 psu,s i have laying around but i should'nt need to as the max power consumption is only 150w according to your numbers the psu powering the rest of my comp has plenty of room to spare for the on board 75w it needs

on another note i seriously doubt that i will max out the card with the games i play, and the monitor i have wont need that much.

also i am a service tech for comercial heating and cooling systems. i know that a furnace isnt a computer, but i have a pretty good knowledge of electrical stuff. a project like this will make me happy to see how it worsks out.

@ sirheck i appreciate your responce, and looked at your link. the point of my post was to not buy a psu. why on earth would i buy a 250w psu like that when i have a perfectly good 250w psu laying around. if worse came to worse, and i had to buy one i would'nt buy that. i was looking at the pc power and cooling 750w unit which i may buy eventually. but the wife would have my head as i just spent over $600 on turning an old comp into a DVR and my new vid card. DVR for her soaps :roll: vid card for my games :D
 

sirheck

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Feb 24, 2006
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sirheck i appreciate your responce, and looked at your link. the point of my post was to not buy a psu. why on earth would i buy a 250w psu like that when i have a perfectly good 250w psu laying around. if worse came to worse, and i had to buy one i would'nt buy that. i was looking at the pc power and cooling 750w unit which i may buy eventually. but the wife would have my head as i just spent over $600 on turning an old comp into a DVR and my new vid card. DVR for her soaps vid card for my games

do you understand how that psu i linked works?

if you have another 250watt psu lying around,
good luck using it :roll:
 

TonyStark

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i guess what im looking for is someone that actually knows. how much current the card draws from the bus, and how much current it draws from the pci-e power connector.
The vid-card will use:

* 75 W from PCI-E slot
* 75 W from 6-pin PCI-e connector x 2 connectors = 150 W
= 225 W max

Divide that by 12 volts and you get about 18.75 Amps MAX current draw.


Now, if you use multiple PSU's, you will need all of them to be connected to the motherboard. I read a guide on another forum about connecting multiple PSU's to a mobo, I'll try and dig it up for you.

EDIT: I can't find the original guide mentioned above. However, you could also try something like this: Multiple Power Supply Guide

hey tony thx for the info man :) and the link is very usefull im very suprized that a guide like that doesnt exist on this site

where may i ask did you get the power consumption numbers for the vid card? after many hours on google i couldnt find that info. also the 8800 gts's i have been looking at on newegg they all seem to have only 1 6 pin connector on the card

if they have 2 connectors i could possibly use 2 of the 3 psu,s i have laying around but i should'nt need to as the max power consumption is only 150w according to your numbers the psu powering the rest of my comp has plenty of room to spare for the on board 75w it needs

I got the info from a respected member on this site.

A PCI-e connector can supply a maximum of 75 Watts. The most Power a card with two such connectors will consume is 225W. The 8800GTX may actually only use 165 W (for example), in which case it still needs 2 connectors.

The only way to find out the power consumption is with a Wattmeter.

I still think you should buy a new PSU. You may be able to pull this dual-PSU thing off but if something goes wrong, you could fry your motherboard and vid-card.

sirheck i appreciate your responce, and looked at your link. the point of my post was to not buy a psu. why on earth would i buy a 250w psu like that when i have a perfectly good 250w psu laying around. if worse came to worse, and i had to buy one i would'nt buy that. i was looking at the pc power and cooling 750w unit which i may buy eventually. but the wife would have my head as i just spent over $600 on turning an old comp into a DVR and my new vid card. DVR for her soaps vid card for my games

do you understand how that psu i linked works?

if you have another 250watt psu lying around,
good luck using it :roll:

:lol:
 

skiplar316

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ok guys here we go after about 5 hours of messin around. mounting the spare psu on the outside of my case. covered up with a nice piece of custom cut & bent sheet metal. rummaging around i found a few spare connectors out of my service van. i managed to get the video card all hooked up. i painted the sheet metal to somewhat match the case it isnt perfect. but at least it dont look like a complete hack job with a psu and wires just layin around on the carpet :lol:

im happy to report that it works just fine so far. i dont have the greatest of games to test my card on. the best being company of heroes i played for an hour with the max settings that will support my monitor. i am truly amazed.

for the past 3 years i have been living with my games at low settings on integrated or the bfg 5500oc 256mb pci card games were playable but never trully great like they are now.

ive got a fluke hvac multimeter and so far it tells me the temps in the psu are going at about 45 c during my 1 hour test run of CoH i didnt break out my clamp on to test the amps but if the temp is alright i dont think i need to.

i think ill use the setup for the next few months untill i decide to get more ram and a monitor then ill go with a new psu and abandon the setup i got now.

ill keep you guys posted if it blows up ill tell you guys about it. just so if anyone else trys it they can make the decision for themselves. and so the rest of you disbelievers can deservedly laugh at me.

i wouldnt recomend some joe just doin somethin like this. unless they have the patience to do it right first, and not have a hack job of psu's, and wires layin around to cause a fire. i put my faith in my skills and the theory of it working. dont do it unless you do the math and research it.
 

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