Basicly to even have the chance of modding a Rad9500 (non-PRO) to a 9700 is if your card has 128MB AND uses the old Rad9700 PCB (they now use a seperate dedicated PCB like the 9500PRO). You then have about a 25% chance of successfully enabling all 8 pipes which is all that seperates this from a true Rad9700 as the 9700PCB with 128MB enables 256bit RAM and obviously the clocks are the same for 9500, 9500PRO and 9700. HOWEVER there's a big chance that EVEN with a 9500 with 128MB on 9700PCB that you'll be left with only 4 pipes, and the perf hit of having only 4 pipes is VERY BIG! At stock speeds the Rad9500 is SLOWER than a GF4TI4200 and unless you enable full AA & AF (GF4TI aren't designed to run with this) the 9500 stays formly behind, considering how little a Rad9500PRO costs it makes sense not to trust to luck ESP since all 9500's now reportedly use their own PCB.
A Rad9500PRO is about GF4TI4400 speeds but obviously much faster with full AA &AF, even with a GF4TI4600 using medium AA & AF the 9500PRO is still faster with FULL AA & AF. JFYI a Rad9500 128MB with 256bit RAM modded & o/c'ed to 400/310 (9700PRO is 325/310) BUT still with only 4 pipes is significantly SLOWER than the lower clocked Rad9700PRO, like 40%. My advice would be NOT to chance to luck with a 9500_128MB but to grab a Rad9500PRO or 9700 and o/c them. The 9500PRO can hit 9700 speeds once o/c'ed and the 9700 often hits 9700PRO speeds when o/c'ed! If you want good perf without risks on a budget look no further than a GF4TI4200 or a 4800SE if the price is right.
But the bios can be flashed on all of them to allow overclocking. Overclocking is supposedly disabled on all but the 9700PRO. I just got my 9500PRO and installed it today. I'm going to flash the bios this weekend.
I've seen benches that put an OCd 9500PRO right at 9700PRO levels in many benchmarks. We'll see....