Originally Posted by aloosh81
hi all i have 650w cooler master psu running 2 8800gt sli ,2 hdd,email@example.com,4 fans , the question is dose the psu has any thing to do with performance ,I'm talking about the stability i run 6 hours prime95 full loud ,no problem it is just the performance i think my system should be better than what it is now and every thing is fine unless the psu is no good??
I recently sold my Asus 8800GTX on eBay, (still have the Aqua Computer Silver special edition waterblock) and bought two 3870X2 vga cards. I used to have one Ultra X2 550w psu. At first I had used this to power just one 3870x2, when I got the second 3870x2.
I bought a Logysis 550w psu more for the convenience of not having to buy two switching connectors for two 4-pin to two 6-pin pcie connections, as the psu locally was on sale for $39...it would have cost more for the connections with shipping/tax.
Getting back to the issue I noticed a drop in my 3Dmark06 score as opposed to an expected increase, when I first installed the second card, with the new psu.
Also, as the other guys on here have posted I was getting some strange crashes with higher clocks...as well as lots of vga error messages at post. Even before installing the second card, the Ultra went south after one week of adding the second 3870x2 and new psu.
I bought a Apevia 680w psu the next day, and my score with the exact same setup went from 12700 to 18700, everything was the same drivers, pcie slots,settings,etc. Also, the crashes stopped and I have been able to oc at higher rates.
I can say that it's recommended by the manufacturer that you have a 600w psu for one 3870x2, but if you've got your psu zolting your cpu,fans,hdds',dvds',fans, it all matters....especially if you've had a psu unit doing this for 6months or longer...most psu are rated for there output within a given heat operating range.
Once you add more stuff into the psu loop this only makes for an increase heat load matching the added demand. Over time other factors such as high ambiant room temperatures can push a psu to the brink.