• Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.
  • The forums have been upgraded with support for dark mode. By default it will follow the setting on your system/browser. You may override it by scrolling to the end of the page and clicking the gears icon.

using external power supply for graphics card

this is come power consumption figures i took with my killawatt meter

1.05vcore no cool and quiet
cpu
138w load
99w idle

so with 138w will a full prime 95 load leaves 62w ish

well from what i got from a german computer site as

4.38A @ 11.89V = 52.1 W pci-e slot
7.82A @ 11.97V = 93.6 W from the pci-e power cable for the hd4850 so that is well below the 120w or 10A that the external power supply can deliver

138w+52.1w = 190.1w that is a bit close to the wire on the internal power supply so i think i will so some undervolting and underclocking of the graphics card to bring the power draw down.

even then i highly doubt that i will be running furmark + prime 95 at the same time.
 
Last edited:
ok ive got the relay and the diodes now i just have to go over to my friends and swap my hd4850 golden sample for his reference design single slot 4850

i have also ordered a lot of new parts for this computer ive got the flu just now and in my fevered delirium i started thinking crazy thoughts like a full water cooling setup, lcd screens and much much more.

my water pump just fits under the hard drive rack and i can get a 80mm radiator and a 92mm radiator to fit on it and i still have a cpu/northbridge waterblocks i want to fit.
but il leave that for now and focus on getting the graphics card working.

i have made up a circuit that will let me use a red/green/blue led to indicate the status of the external power supply. when the computer is off and the power supply is connected the relay is open and turns on the red part of the led to let me know that the power supply is connected ok and when the computer is powered up it will close the relay and connect the blue part of the led letting me know the graphics card has power.

33nvt6a.jpg


the new parts ive ordered for the computer are

aluminum sheet for the front. http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=150380922094&ssPageName=STRK:MEWNX:IT
new usb ports for the front http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160363354028&ssPageName=STRK:MEWNX:IT
new power switch http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160369271033&ssPageName=STRK:MEWNX:IT
reset switch http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=320433577305&ssPageName=STRK:MEWNX:IT
rgb led's http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=380127739848&ssPageName=STRK:MEWNX:IT
led holders http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=350232770025&ssPageName=STRK:MEWNX:IT
usb lcd display http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=220485014364&ssPageName=STRK:MEWNX:IT

im going to start a project log soon once i get the graphics card in.
 
Last edited:
Seems alot of messing about to me ! Whats wrong with just flicking the switch at the wall socket ?
 
Sir_Real said:
Seems alot of messing about to me ! Whats wrong with just flicking the switch at the wall socket ?
Click to expand...

lol that would be easy wheres the fun in that.
 
Looking good Geofrancis. Didn't want to waste that other switch pole on the relay hmm? At first I thought your LED was an op-amp and I was really wondering wtf you were doing then I read the post. :laugh:
 
Lazzer408 said:
Looking good Geofrancis. Didn't want to waste that other switch pole on the relay hmm? At first I thought your LED was an op-amp and I was really wondering wtf you were doing then I read the post. :laugh:
Click to expand...

well i wanted to run an op-amp but i didnt see the point :laugh:

if i get everything i want into this computer actually into it then it must be some kind of record for the most computer parts stuffed into less than 1 cubic foot.
 
Last edited:
I have .1812 cubic feet to cram 12,000 3dmarks into without burning the carpet.
 
Lazzer408 said:
I have .1812 cubic feet to cram 12,000 3dmarks into without burning the carpet.
Click to expand...

nothing liquid helium wont fix lol

i also discovered a natural coolant that i use when things go on fire....i piss on it
 
Last edited:
Geofrancis said:
nothing liquid helium wont fix lol

i also discovered a natural coolant that i use when things go on fire....i piss on it
Click to expand...

I hope you unplug it... unless your into that kinda stuff... in which case I still hope you unplug it. :roll:
 
no thanks, that one's NOT an urban myth.
 
does anyone know where in the uk i can get some very thin bolts about 1mm that i can use to secure a northbridge waterblock to the motherboard?
 
Geofrancis said:
does anyone know where in the uk i can get some very thin bolts about 1mm that i can use to secure a northbridge waterblock to the motherboard?
Click to expand...

Do you have a hobby shop in your town? Some hardware stores also carry very small machine screws but they might be on a seperate rack then the other nuts and bolts.
 
theorw said:
Now why whould u do taht when its known that u shortsircuit the green mobo pin of the psu in need with any ground....
Click to expand...




Short circuiting is not a good thing.

I had the extra MB sitting around and it was easy to do. didn't have to mess with my main RIG MB. Kept the video card PSU out of the case. Just ran the power cables through the holes in the rear of the ANtec 900 case.


It was just an experiment. I did end up pulling off my best Vantage score though.

http://service.futuremark.com/resultComparison.action?compareResultId=1411203&compareResultType=19

Performance gain from multi-psu set up is marginal and questionable.


I was trouble shooting my main Corsair TX650W to see if I should upgrade PSU.
Results proved to me that I didn't need to upgrade PSU.


Best to go with a good PSU that is rated for devices to begin with.
 
Lazzer408 said:
I did a few tests on my HD3870 to see what it was drawing off the 12v connector.

DC amps / activity

1.90 / Post and booting.
0.25 / Windows desktop.
2.6-3.2 / 3dMark06 with the highest current draw being Firefly Forrest.

I read this card is 80w. I also read the standard for 6-pin is 75w and 8-pin is 150w. Divided by 12v = 6.25a and 12.5a respectively.
Click to expand...

I wanted to mention my results with the 4850. It's bios modded for lower idle clocks and fan control was altered. Readings taken from 12v connector. Quite a difference from the 3870. :confused:

DC amps / activity

3.35 / Post and boot
2.08 / Windows desktop
6.14 / 3dmark Firefly Forest
 
Lazzer408 said:
I wanted to mention my results with the 4850. It's bios modded for lower idle clocks and fan control was altered. Readings taken from 12v connector. Quite a difference from the 3870. :confused:

DC amps / activity

3.35 / Post and boot
2.08 / Windows desktop
6.14 / 3dmark Firefly Forest
Click to expand...

well that looks less than i was expecting so it shouldnt have a problem running of the 120w 10a psu.
 
i have came up with a plan for my computer to fit all the watercooling components i will need into it.

27xe0cl.jpg


its gonna be tight!
 
Last edited:
All :respect: Microsoft Paint. :rockout:
:D

Looks good IMO. Good luck!
 
This is all crammed into that case? haha nice.
 
Last edited:
Any pictures of fire? I wanna see some burning silicone damn it!
 
Geofrancis said:
yea its gonna be real tight! you should try and get some watercooling into your build.
Click to expand...

I already have to modify the powersupplies heatsinks to get that to fit. lol Trust me there's no more room except for this little pocket under the... How small do they make pumps? :D
 
You must log in or register to reply here.
Back
Top