Yes, I realize the 5770 goes for around $160, but my PSU is only 300w. Now, I believe I could get away with a 5750 on 300w, but I'm not going to risk a 5770 so I'll have to upgrade my PSU for around $60 if I go for the 5770.
My monitor's max resolution is 1680 x 1050.
I'd have no problem paying $20-30 more for the step up for the 5770, but I think it's pretty clear that the upgrade is not worth almost a hundred bucks?
am I making a big mistake risking a 5750 on Bestec 300w power supply?
Nah, it doesn't need a 400w, a quality 300-350w PSU should handle an HD5750(it barely uses it's power connector if at all.)
That said Bestec is definitely not a quality brand and I wouldn't put an HD5750 in that thing so you will need to upgrade your PSU anyway if you want a card of that caliber.
Newegg is giving me a hard time about changing my order (even though it would be in their best interests as it's much more expensive ).
How risky would it be to run the 5750 with the 300w psu? I realize it's impossible to quantify, but are we taking about a huge risk or a slight risk? I'm not overclocking or anything so my system shouldn't be a big power drain. I have a 2.6Ghz 810 Phenom II X4.
Bestec is so OEM. We have the newer 24-pin 80 certified unit in an HP downstairs and it's running an x800xl with no problems.
It would be worthwhile to replace the PSU with a good 450 watt at least of a dual 12+ volt rail of at least 26a. Or..
Go all out and get a 600 watt psu for a few bucks more and leverage that 12v+ to around 48a so you can run the bigger cards. (eventually, or you can always use it in a new machine later if you choose)