9800GTX + Antec 450W Smart power PSU, compatible?!

jasku

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Nov 18, 2006
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Hey Guys,

after a lot of deliberation, I have decided to go for the evga Geforce 9800GTX against the 3870X2

Now my concern is, will this GPU run with my current sys?

Asus P5WDH-Deluxe
C2D E6400 oc @ 3Ghz
Corsair 2x1 Gb 800 mhz
ATI Radeon 1900XT 256 mb - this one has a 4 pin connector?..not sure
1 Seagate 320 GB HDD
1 SATA DVD RW
Antec 450 W Smart power

I checked out the rating on the SMPS it has 2 +12v rails, one with a rating of 15A and the other 17A

I plan to upgrade to a
9800 GTX - immly
Q6700 - in a week or so
One Raptor 150 gig (this one can wait)
One Sony DVD Rw - already have it..too lazy to attach it!

My order is on hold untill I get the go ahead from you guys!.

THanks.
 

jasku

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pretty kool man.. I ve read in most threads that a min of 600W PSU would be good for todays GPU's, on this calculator with my future needs also the total wattage came upto on 380W!....surprising..hope the calculator is right.

Thanks.
 

I wouldn't bet on that!! The Antec 450w SP PSU only has 22A total on the combined 12V rails. I wouldn't chance this PSU on a Quad (125W) and a 9800gtx. I'd go with at least the 430w Antec Earthwatts PSU, which has 30A on the combined rails. I wouldn't attempt to power up your rig with that PSU. It is probably already at it's upper limits and with capacitor aging is pushing things. You can chance it, but with all of the $ that your putting into your system I'd just play it safe and get a new PSU. The Corsair vx450w PSU is also a good unit too.
 

pauldh

Illustrious

Agreed.
 

Zenthar

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If you plan on reusing the PSU for other builds, then I recommend ~700W (should last you 2-3 builds if you upgrade every 2 year). If you just want something that works for the current config, I always suggest 500W+ for single GPU and 600W+ for SLI/XFire (paying close attention to the rail's voltage).
 

jasku

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As i said initially my current PSU has two 12V rails , one reads 15A and the other 17A, putting them together its 32A,,,,is this not enough...or am being stupid??!
 

Zenthar

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As everything in live, nothing is that simple. I found the spec for the PSU and it seems the 12V rail is limited to 240VA total so the combined amperage of both rails, cannot exceed 20A, sorry.
 

A_Dying_Wren

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Hmm... The thing about power supplies is that they degrade over time. For future proofing get a higher rated one. Will also help if u plan to OC.
 
I'd go with the Corsair tx 750w PSU ($120 after MIR). It has 4 x 6+2 pin PCI-e power connectors, so if you wanted to power up 2 9800 gtx's you could and wouldn't need any converter cables. Also I'd consider the PCP&C 750w Crossfire PSU. There are plenty of good PSU's in your price range, but these 2 stand out pretty good. The Corsair is economical and solid and the PCP&C is more expensive, but is very good too.
Corsair TX 750w PSU, $130 - $10 MIR = $120
PC Power & Cooling Silencer 750 Quad (Crossfire Edition) EPS12V 750W Power Supply for $171 shipped!!
 

jasku

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Dude both the PSU;s u have suggested have only one 12v rail....from I read around in the forums, guys say that the more the 12v rails the better....can u pls clarify this concept?,,,, I am leaning towards the Corsair..cause they have service centre in India!

$99 shipped no rebate and GF8800GTS SLI certified would be a good option. Quiet and made by Seasonic.


But you don't need such a beast for a single GPU. 30 amp on the 12 v would more than do it, like an earthwatts 430W.

Yes ur rite..but a little future proofin for an extra $29 worth it I guess!
 
Here's 1 of many articles on the multiple 12V rail issue. There are many more, but I'm just quoting this one:
Multiple +12V Rails
As power supply capacity increased, the ATX power supply standard was amended to include:

3.2.4. Power Limit / Hazardous Energy Levels

Under normal or overload conditions, no output shall continuously provide more than 240 VA under any conditions of load including output short circuit, per the requirement of UL 1950/ CSA 950/ EN 60950/ IEC 950.

—ATX12V Power Supply Design Guide, version 2.2
This is a safety limit on the amount of power that may pass, in case of a fault, through any one wire. That much power can significantly overheat a wire, and more would be likely to melt the insulation and possibly start a fire.

Because implementing one current limit per wire is prohibitively expensive, and the limit is far larger than the reasonable current draw through a single wire, manufacturers typically group several wires together and apply the current limit to the wire as a group. Obviously, if the group is limited to 240 VA, so is each wire in it. Typically, a power supply will guarantee at least 17 A at 12 V by having a current limit of 18.5 A, plus or minus 8%. Thus, it is guaranteed to supply at least 17 A, and guaranteed to cut off before 20 A.

These are the so-called "multiple power supply rails". They are not fully independent; they are all connected to a single high-current 12V source inside the power supply, but have separate current limit circuitry. The current limit groups are documented so the user can avoid placing too many high-current loads in the same group.

This works in the same way, and for the same reason, as the many small circuit breakers in a circuit breaker panel as well as the main supply breaker. And just like typical domestic wiring, multiple outlets are connected to each circuit breaker for reasons of cost.

Originally, a power supply featuring "multiple +12V rails" implied one able to deliver more than 20 A of +12V power, and was seen as a good thing. However, people found the need to balance loads across many +12V rails inconvenient. This problem was exacerbated by the fact that the assignment of connectors to rails is done at manufacturing time, and it is not always possible to move a given load to a different rail.

Rather than add more current limit circuits, many manufacturers are ignoring the requirement and providing "single-rail" power supplies that omit the current limit circuitry. Although capable of starting a fire under the appropriate circumstances, there have not been a noticeable increase in accidental fires, and as of 2008, product safety testers like Underwriters Laboratories continue to approve the supplies.

For a time, power supplies were marked and sold as having multiple +12V rails, although no current limit circuitry was included. As of 2008, having only an overall +12V current limit is seen as a desirable feature, and "single-rail" power supplies are advertised and sold as such, although it is still common to find power supplies for sale that falsely claim to have multiple +12V rails.
Link to quote

Basically the multiple 12V rail situation is generally a marketing ploy. If you have a quality PSU than it doesn't really matter if it states that is has multiple 12V rails, because in reality it is probably just a single 12V rail.