Q-Tec PSU's

how hot, gpus are happy up to 95C+ depending on the chip, some are hotter. yours is 100C. http://www.geforce.co.uk/hardware/desktop-gpus/geforce-...
are you running the latest drivers?
what games and what settings. for instance Bf3, will need more memory than the 550ti's have, and in sli each card uses its own memory, i.e. you don't add the memory together.
Given that peak usage for these is 116W each that's 232W on gpus, the rest of your system will be using another 150W. so you should be fine. Also note that there are plenty of single GPU's that use about >225W so an SLI certified PSU should not be needed.
if your power usage was any higher i'd be suggesting a better PSU, but at 60% of PSU max I don't see that we have problem.

Found one on Ebay, only has a 25 amp 12v rail, does not come anywhere near being a 650 watt power supply
http://www.ebay.com/itm/Q-TEC-PSU-ATX-650W-Triple-Fan-P...

Thanks for getting back to me my friend. These cards are getting really hot and it's just in the space of 10 or so minutes. It's not my machine so I don't want to damage anything.My own machine is a InWin Dragon Rider tower,a GigaByte GA-990FXA-UD3 motherboard,the same Phenom2 CPU,2X Zotac 550Ti'S,8Gb Ram and a Coolermaster 700W PSU..I play all the new games at High or Ultra settings with quite decent frame rates.(well good enough for me that is)..With my grandson's machine,it doesn't matter what settings(ultra,high,medium or low)frame rates are low and games like BF3 lag.A review and test of this Q-Tec PSU on the Bit-Tech website advised on steering well clear of this product as it wasn't up to the job..The PSU is the only part of his machine that is old every thing else is new and OS is Windows 7 64Bit.Am I right in thinking that an increase in the low voltage would cause components to overheat or have I got that wrong.I have an old Hyper 550W PSU would it be ok to try this on his rig.His Motherboard is an MSI 990FXA-GD80.Sorry for rabbiting on for so long and thanks again for your comeback.Best Regards Grandad John

Nice of you to get back to me.I had never heard of this company and have always went for brand names.You seem to get a better warranty and a better product. The Bit-Tech website did a review and test on this Psu and didn't think much of it.I have a Antec 1000W In one machine,a cooler master 700W in another and a Hyper 550W in another.The Hyper went after a year and a half.I sent it back and got a brand new replacement without any hassle. Q-Tec give you a warranty but don't tell you for how long.Thanks again all the best Grandad John

I have all the latest Nvidia Drivers

the psu will not make them run hot. again how hot do you think is hot.

Hot as in you cant hold your finger on either card for long. I've been into computers since windows 95,. have built ,rebuilt and repaired quite a few now.Have never seen cards get this hot before and I've bought a lot,from AGP's up through the ranges of the GeForce series..I run 2 Zotac GTX 550Ti's in Sli and have played BF3 in high settings with no problems.In fact most of the new games with decent enough frame rates.(well for me anyway,not into overclocking).Went on to a couple of other Tech sites and got reply's right away saying that a faulty PSU will most definitely cause graphics cards to overheat.Was advised to stop using the machine as it could end up with damage to other components.This Q-Tec Psu doesn't even have a on off switch and a couple of other guy's said it didn't have enough power. I've sent for a CoolerMaster 750W 80p bronze and hope that this solves the problem..If this doesn't cure it I'll be back grovelling with egg all over my face.Thanks again for your time and I'll be in touch when I get it installed. All the best Grandad John...

can you use speedfan/msi afterburner to track the actual temps. I agree it sounds bad, but they could just be getting rid of heat from the chip. I'd like to know actuals. Remember that an 80C chip temp is not unusual, and that would create a very hot heat sink. Both of the above software can show graphs so you can see what it was like whilst gaming.

This could be the cause of your poor frames, if they are throttling, the next question is why are they throttling. The fans are spinning aren't they?

Hello I'm back and I think I've found the problem.(hope so anyway).My son built the machine but as he's working in Angola he want's me to rebuild it.On stripping it down I see that the MSI 990FXA-GD80 has an 8 pin ATX power connector but only a 4 pin is plugged in at 3-4-7-8.This Psu only has 1x4 pin connector and on looking more into it was on sale in 2004 for Intel P4's and AMD 3's.If I'm wrong I apologise now but in the mean time I'm just waiting for the new Psu to arrive.Best Regards Grandad John.

good call, could be causing all sorts of weirdo symptoms. Come back to us regardless, as it'd be interesting to know. Thanks.