I am having the exact same problems. See my thread a few posts below yours titled "" (Sorry I cannot post links yet) 
 
I had always thought the voltage was unlocked on the 750 TI FTW edition. I saw this post on youtube, where they were able to get +115 on the GPU core clock and upped the voltage by +12 mV. (Again, no links. Search "Evga GeForce GTX 750TI FTW overclocking using Precision X"). The most I can get is +20 GPU and I can't seem to tweak the voltage at all.

The most likely won't increase the power target, as almost all Nvidia based cards are loved to 106%. You may be able to find a hacked bios in the future though for a low end card it may be unlikely.

They most likely included that 6-Pin connector to increase stability more then anything. As the 750 Ti will almost saturate the PCI-E slot in terms of the power that it can provide. The connector will allow the card to draw from two sources meaning you will have a better chance on an over clock it isn't sure thing though.

Hi guys, new to the forum, doin a bit of overclocking on this card, everything is stable, wondering if this is decent and what other people are getting...
GPUCore clock-1402
Memory 1699.3
 

Hey Stefan2,
Thanks for the reply and info.
unfortunately +75 seems to be about the highest stable i can go on core clock.(but i'm ok as this was decently factory overclocked to begin with, without touching anything mine ran at 1332mhz out of the box)
i'm more curious on the memory overclocking.
i've gotten it up to +700, and it seems fine,
i'm a little afraid to go past that...
i'm curious where have you topped out on your memory clocks?(stable)

yes, I believe voltage is locked on these cards unless u flash mod bios. Hmm, that's the lowest memory over lock I've seen so far. Mine is stable up to +650. Even at +700 no freezing, just very little amount of artifacts, not even noticeable. +80 on gpu and it freezes though. Never seen over 60c yet either.
 

crysis3 yes
bf4 I don't have installed, but I will install it later today and see.

hi guys! im new to the forum, but ive been playing around with my Asus 750 ti oc bios much and clearly also even with ocing.
my card stock setting is 38.500 tdp , 1085 mhz core 2700 memory. 
i did a lot of tries , but actually im keeping up my TDP like this :


30.000
100.000
100.000
 
30.000
75.000
75.000
 
30.000
100.000
150.000
 
means im using power target at 150% , since i have a 700 watt alimentator and i have a lot of free power to spare(my pc doesn't require much)
 
and this change made my card so much more powerful both in benchmarks and games, ive seen a consistent fps increase
 
ah im forgetting, my basic voltage on the card was i think around 0.950 and 1.050, im forcing it to 1.2v plus i also use force costant voltage on afterburner and +100 mv on afterburner to get sure i can reach the max voltage i can, those maxwell cards suffer of voltage over 1.300 - 1.350 in case of you hard mod them, but 1.200 is almost safe, i red it on a lot of forums.
 
im mainly a gamer and i often stream my games so i need an oc super-super safe because i would hate so much if my oc crash while im streaming XD i use 1398 core (+213) and 3150(6300) (+450) memory for a 365, daily overclock setting, it never crashed since before december or so so i think this is stable enough(i use pc for gaming and streaming 6-8 hours all days) 
for bench i can stand with 1437 mhz core and 3450 (6900) memory, but clearly this setting hold even just for some bench and not more, but i love to try hard the max my card can pull out sometimes,
im not sure if i read this 3dmark benchmark page correctly, but if im not mistaking, i think in the details of the benchmark it is saying im fifth on the 3dmark ladder for possessors of my same cpu (i5 4670k) and vga (nvidia 750 ti)
 if you can let me know how does this score appear for a 750ti and considering my processor has air cooling (and stock) so it is at 3.6....
the very curious curious think is also that in the top 10 placement there are guys with their 4670k at 4.9-5.0 frequency, and most of them are behind me as global 3dmark firestrike score even if i benched at a super ridicolous 3.6 frequency XD and that frequency affect global score soooo much believe me XD. anyways i think all of them (first one included are pretty far from my graphic score (5543), the first one has a 5426 graphic score for example.

Does anyone have a custom bios that you can over clock further on the gtx 750ti FTW?

When a thread is over 3 years old it is always best to start a new thread.