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power supply hurting graphics card performance?

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September 27, 2008 8:21:53 PM

Hey all,

Have a quick question, I am just checking into it but i am seeing that my power supply doesnt really meet my graphics cards requirements. The Specs are the following:

Graphics Card: 512mb Sapphirehttp://en.wikipedia.org/wiki/Sapphire Radeon hd3850pro agp
Power Supply: Thermaltake 450watt TR2 RX Cable Management W0146RU

Basically the wattage output meets but my power supply only has 20amps on the 12v rails when my graphics card requires 30amps. I have had the card in for a couple weeks and it seems to run prefectly fine. Some games I do get some shuttering/fps drops/slow down but that is in like Crysis, and some other high end games but I am sure that it from my computer not being good enough, not from the power supply. (will post full computer specs at bottom of post)

So Basicaly I was wondering if this is hurting my performance quite a bit? I bought the power supply a couple months ago because my old one died. When I bought it i didnt intend on buying a new graphics card. If I did, i would of bought the 550watt model that has 33amps on the 12v rails. Now my graphics card uses a 2 molex connecter to a 8pin pci-xpress adaptor to get power, and I do have each molex connector on separate rails so I dont know if that helps things. So I would hate to have to buy a new power supply because I cant return this one and I have and probably never will have a use for it. If that is what I have to do....I will do it though. Thanks for any help guys!



Full comp specs:

OS: Windows XP Home with SP3
Motherboard: Asus A8V-X VIA K8T800pro/VT 8251
Processor: AMD Athlon 64bit +3700 2.2ghz socket 939
Ram: 2gb (2x1gb) OCZ Platinum pc3200
Graphics Card: 512mb Sapphire Radeon hd3850pro agp
Sound Card: VIA Envy24 HF
Hard Drives: 200gb/500gb Western Digital 7200rpm 8mb cache IDE and 500gb Seagate USB External
Power Supply: Thermaltake 450watt TR2 RX Cable Management W0146RU
September 27, 2008 8:38:13 PM

Well, i been in your shoes. Bought a 7950 GX2 didnt have a 6 pin connector for it so i tried crysis w/o giving my graphics card ANY power at all, i got a total of 7 FPS all low settings. Got my 6 pin connector tried it again, got 30 fps medium/high settings with a PSU that gave me 12 amps lower than i was suppose to have and at the same time no stuttering. I finally got my new psu which exceeds my requirements and no difference in performance at all, no extra fps nothing.

I know this didn't help but even though i lacked 12 amps it worked just fine. But i do know id buy a 1000 watt PSU if i were you for the simple fact that things require more power now days and it seems to be increasing.

That's my suggestion, a new PSU since it wont kill you and can use it with a new system when you upgrade.

But OC your cpu before you do i just remember my pentium D 2.66 GHZ bottle necking my geforce 8800 GTS 320 MB.
September 27, 2008 8:54:14 PM

That 30amp requirement is for the whole system - the card itself doesn't draw that much.
Without overclocking it only pulls about 63W underload:
http://archive.atomicmpc.com.au/forums.asp?s=2&c=7&t=93...

According to this little tool: http://web.aanet.com.au/SnooP/psucalc.php
your ok in watts and amps (made some educated guesses on some of your stuff).

Having said that, your PSU has two rails, one with a max of 14A, the other 15A. One is dedicated to the CPU, the other is for the rest of the system. So say you have 15A max for the rest of the rig - and not even that since some will go to the 3.3 and 5V rails (can't tell from online info what the exact breakdown is). Call it 12A avialable to the rest of the system when the PSU is new (like it is now).

The PSU itself is only considered a tier 4 psu: http://www.xtremesystems.org/forums/showthread.php?t=10...
Hard to say but it might not hold up well over time.

Bottom line is right now your probably ok - but as the PSU ages and/or if you try to overclock the graphics card or the cpu, you might experience some issues.

I'm a bit conservative myself so I might trade up for a better, larger PSU - but you really don't need anything close to a 1000w - a good soild 500/550W with a single rail above 30A will do you just fine.

Sdrac

-- oh, and I agree with Chaos that if you want to get more out of that GPU, you should consider OC'ig the cpu. Its only a single core so you'll be limited a bit anyway, but all the more reason to OC it.
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September 27, 2008 8:58:48 PM

If he is right than you need to OC that cpu.
September 28, 2008 1:32:01 AM

I have checked into it.....my motherboard doesnt seem to have any overclock settings in the bios. Unless there is another way to oc I think i am stuck.......I have been thinking about picking up a 2.4ghz 2mb cache dual core socket 939 on ebay for like $50 to $60 bucks. Figure that would be a big step up and wont cost too much. What you guys think? Thanks for the info though!
September 28, 2008 2:38:48 PM

I checked your MoBo manual - you do have some ability to OC.
With your current processor you don't have an unlocked multiplier so you'll have to adjust the HT freq (called FSB) in your BIOS.
If you decide to do that, post back as there are some tricks to OC'ing these setups. You're probably not going to get a big overclock though - this board line wasn't really made for OC'ing.

As for the dual core 939 - which one exactly? You should check to be sure the processor is supported with some version of BIOS for your Mobo before you purchase.

!