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PSU For 9800 GTX

Last response: in Graphics & Displays
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March 21, 2008 6:37:34 PM

I currently have a 600 Watt PSU and a 100 Watt dedication PSU to overclock my current graphics card. Is this going to be enough power for the 9800 GTX comming out?

More about : psu 9800 gtx

March 21, 2008 8:11:36 PM

It's power draw shouldn't be too bad, in theory it could run off of just one pci-e connector since g92 GTS cards can clock to those speeds and beyond on just one connector.
March 22, 2008 3:50:58 AM

My 8800GTS 512 is clocked higher than a 9800GTX and is on a 620W PSU, and 620W is rated for all SLI setups, so you are way over what you need, no worries.
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March 22, 2008 2:35:41 PM

You could run it on a 450 watt psu, if you wanted!
March 22, 2008 3:13:17 PM

The new GTX needs two six pin Pcie connectors, if you have that it should be no problem. But I for SLI it will depend how much other power you are using, it wil probably work if you have a good PSU, but I'm not 100% sure.
March 24, 2008 12:51:30 PM

LAN_deRf_HA said:
in theory it could run off of just one pci-e connector


I've seen pictures of the 9800GTX, it needs 2 6pin adaptors to power it.

To the OP, you should be fine.
March 24, 2008 7:43:34 PM

No one stated otherwise.
Anonymous
a b U Graphics card
a b K Overclocking
April 6, 2009 10:39:22 AM

Power supply requirements just aren't as high as most people assume they are. Here is a good PSU calculator:

http://extreme.outervision.com/PSUEngine

If you input all your hardware you'll find that your wattage requirements are going to be pretty low, probably under 400w with a SLI setup and multiple drives. The important thing is to look at your total amperage of the 12v rail(s) since that's what the majority of your components would be running off of. You can take the combined amps of all your 12v rails and then times them by 12 to find out how many watts they will put out.

Hope that helps!
a b U Graphics card
a b K Overclocking
April 6, 2009 11:48:26 AM

Quote:
You can take the combined amps of all your 12v rails and then times them by 12 to find out how many watts they will put out.



No, you can't, there are very few power supplies can have the rail ratings added to tell the actual output, you need to know the wattage available to the rails to determine the actual amperage.

I'll use my 550 watt psu as an example;

4 x 18 amp 12v rails = 72 amps
72 amps x 12 volts = 864 watts , not possible with a 550 watt psu

Since the wattage available to the 12v is marked on the label as 492 watts I know that the combined output is actualy 41 amps
Anonymous
a b U Graphics card
a b K Overclocking
April 6, 2009 11:56:53 AM

Do you have a link to your PSU specs so I can examine this? I'll admit that my PSU thinking is a couple years old, I'm trying to get up to speed.
a b U Graphics card
a b K Overclocking
April 6, 2009 12:26:04 PM

Quote:
Do you have a link to your PSU specs so I can examine this? I'll admit that my PSU thinking is a couple years old, I'm trying to get up to speed.



April 6, 2009 1:10:50 PM

Yeah you're right about the Amps not adding up DellUser1 - but that is just because 18A is the most that is stable on a single rail. (You know all this already I assume) and as it says 41A is the most for the sum draw of all 12V rails. If you are worried about rail Amperage there is a simplified solution for those who don't want to have to worry about using separate rails - just get a corsair single rail TX series PSU. (its not necessarily better - just an easy way out)
Anonymous
a b U Graphics card
a b K Overclocking
April 6, 2009 1:21:51 PM

Thanks for the pic. I sort of have to take everything with a grain of salt any more because there is so much information (and misinformation) about PSUs going around right now that its hard to sort out what is actually factual. I suppose it make sense although theoretically if the rails are rated 18A each then each should be able to handle 18A simultaneously and still remain stable. I suppose there is another factor at play here that I don't really understand - heat perhaps?
a b U Graphics card
a b K Overclocking
April 6, 2009 1:36:03 PM

Quote:
I suppose it make sense although theoretically if the rails are rated 18A each then each should be able to handle 18A simultaneously and still remain stable. I suppose there is another factor at play here that I don't really understand - heat perhaps?

18 amps is the max rating for each rail, more often than not the OCP is actually set a little higher, but when combined they won't be able to output thier combined "rated" output.
Heat can be a factor, but it's not what we're talking about here, it's the wattage that is provided to the 12v rails that will determine the total combined output.
Heat comes into play when talking about total ouput.
Most generic power supplies are rated at 25c, when they reach the 40-50c actual operating temperature they will fail to provide thier rated wattage ( can be as much as 50% less ), a good reason to look for a 40 or 50c rating when purchasing a psu.
April 6, 2009 1:37:44 PM

Delluser is the man to ask about this stuff of course - but there can be many factors at play here. If you're overclocking the CPU sometimes draws lots of power over micro second spikes (from what I have heard -don't have the empirical evidence for this) - which is why it is good to have some buffer room if overclocking, even if you read on Toms or somewhere else that there wattage use was inside your PSU specs. Heat shouldn't be an issue if you are not constantly running at load near the max rating for prolonged periods. If so you need to take in consideration the continuous power rating - which should be an indicator of whether or not heat will be effecting your system.

Delluser1 posted this awesome PSU calculator link - its great for predicting both stock and overclocked PSU needs:
http://web.aanet.com.au/SnooP/psucalc.php

!