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up gr4aded from 4870 to a 4870X2 and getting lower fps ?

just tested intel burn test and fur mark multi gpu and the 12v's are droping to 11.21/10.59/11.21 on full load and on idle its about 10.87v
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That unit is fluctuating by roughly 6%-10% on the 12v rail, which is not good news for any device feeding off of it. You would expect +/- 5% on a given voltage under the ATX spec. for a power supply unit. It may have a bit of power to spare elsewhere, but it will be on the 3.3v and 5v rails (they should appear within spec) which aren't much use to you in this case.

Using this handy tool: http://extreme.outervision.com/PSUEngine; I worked out a rough theoretical total for your complete rig of around 578W - 623W @ 90% system load, 352W-402W at about 50% and 642W-692W at peak.

TT650 would be just about enough to hold it all together under most use scenarios, but it will hold the system back when its power draw spikes, which is not 100% of the time, yet it happens often enough to make a difference. Inconsistent gaming performance with dips in the FPS numbers is a prime example of that.

I would swap that TT850 in for a quick testing spin. Its 12V outputs 3 and 4 are rated for 30A max, which should be more than enough to keep HD4870x2 happily fed and will keep the rest of your system stable.

As for an upgrade, look at a more efficient 650W unit with more current on the 12V rail or something in a 700W-750W range. OCZ, Corsair and BeQuiet! units spring to mind, but this end of the market is so over-saturated, almost every listed manufacturer has something to offer here. Just watch out for overall efficiency, 12V output and price in accordance with your budget.
 
so if i continue to use it will i be running the chance of breaking any of my componants ? I noticed when i installed the 4870X2 i was unable to run at 3.8ghz any more and had to lower my clock down to 3.5ghz, so its all making sense i could drop the the OC down to 3ghz. Then undervolt the cpu and gpu and underclock the gpu to put less stress on the poor old power supply.Will this be causing damage to the psu with this amount of load i'am puttin on it as i would like to possibly sell it to recoupe some cost for a new one
 
lol, a key bit of information there! :)

If you are on the limit of the power supply I recommend you get a new one. Things last a lot longer if they aren't constantly on full throttle, and less likely to break.
 
iam going to i've just order a q6600 as well so i shouldnt have any cpu bottle neck when its all up and running just gotta get a good 850w psu :rolleyes: this 'budget' htpc has spiraled out off all proportion
 
It will be fine mate, my Be Quiet PSU done that with my i7 @ 4.2ghz and a 4870x2, would suggest getting a bit more for some headway though if you can, the 4870x2 is one beefy card to power!
 
a sliverstone strider 750W or another Thermaltake 850w the same as whats in my i7 Rig what would you you do as the thermaltake has got more amp's on its 12v rails so should be a lot better for my 4870x2
 
the thing is i can get one for £50inc as i dont want to be spending loads and my i7 will be a nightmare to take the psu out off it and as i say if it aint broke dont fix it lol
 
i know what you mean just i thoght with teh 12v so low it must be the psu so i've ordered a Toughpower 850w HX which the review's say they are as stable as the corsair one's so should have no power problems and also got a q6600 so hopefully no bottleneck ill just have to wait and see
 
well got some good news installed the new psu now the lowest it goes is 11.4v this is just with in the 5% +/- but the fps is still not going over 40fps in farcry 2 ao iam now asuming its the cpu just waiting on the q6600 to turn up now will post more up dates once that is in
 
yup well just this second got an email off the guy and he's sending it out today special delivery so ill defoo get it tommorrow ill re build my rig and see how it goes
 
got my q6600 this morning and at stock 2.4ghz fps have gone up from 40 to 53 in farcry 2 bench mark so defo less bottlenecking
 
Hmm which other games did you run that you recorded frame rates for? Maybe I can do a comparison against my system to yours as well?
 
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