Question regarding Q9550 overclock past 3.5GHz

[Neurotypical]

I'm trying to get some more life out of my nephews old Q9550 system. The specs are as follows -

CPU : Q9550 - 8.5x412 @ 3.5GHz 1.184V
Ram : OCZ 6400 @ 1066 1.888V
MB : Gigabyte ep43-ds3l
GPU : Sapphire 4870 1GB
PSU : CX 600w Corsair

I have it stable at 3.5GHz after 12 hours prime95 test and the cpu hits a max temp of 58 C.

This is adequate since he had it at stock settings before but I don't know why the computer won't POST if I set the multiplier past 412. It just restarts and defaults back to stock speeds. My temps are fine and it's running very stable at low voltage (low IMO). If I put the multiplier up past 8.5 x 415 the computer refused to boot. I know the cpu can handle upwards of 1.3V according to a lot of post I've found on the forums so I'm at a loss as to what is causing the problem. I've tried taking the 4870 and putting in a Geforce 210 (which I use in my kitchen PC for the hdmi port) since it uses significantly less power but this had no effect.

I'm thinking it's a memory clock issue however I have it at 1066 up from 800 and tests have all showed the system is stable. I'm at a loss here, if anyone has any suggestions I'd greatly appreciate it.

 

[chris987]

are you sure you have isolated ram clocks, as FSB overclocking affects them, as pcie also. it can certainly lead into instabilities. 8.5(multiplier) x 415 (Front Side Bus) = frequency. have a pick here , it will defenately be of a help!

http://www.tomshardware.co.uk/forum/259899-29-core-overclocking-guide

there isnt any practical gain aiming for an even higher clock! 3.5ghz is very good which allows to make good use of a gpu upgrade! i think this is a good time for a present to your nephew!

 

[Neurotypical]

I had changed the ram to handle 2.6 x FSB and it's OCZ reaper which i know can handle up to 2.2V so I thought I could get more out of the cpu if I clocked the ram a bit higher. I think this is probably my problem. At 3.5GHz I think he'll get some more life out of the system before he needs to upgrade. I picked up two EVGA SSC GTX 960 cards for $180 Canadian and am running two in my own rig and am going to give him one for his birthday.

I have a feeling that the gpu is a little more than his current system can utilize to it's full potential but at least he'll have a decent card to use for now and can keep it once he upgrades the rest of his components.

 

[chris987]

the gtx 960 is on par with gtx 670. there will be bottlenecking depending the game of course, but in general it will do just fine!