WTF! Is my 7750 actually a phenom?

[dingleberrydorkbutt]

I just assembled a new system based on a 7750 Kuma in a Biostar TA790GX 128 motherboard. I actually ordered the A2 version of the MB and the box said that it was an A2 but the board has 128 on it and cpu-z says that its a 128. But that's a sidenote and may not have anything to do with this.

I immediately over clocked it to 3.2 and kept playing with it but never could get it to run stable in prime95 or amd overdrive stability testing. Finally, in desperation I clocked it back to 2.9 and when I rebooted, windows says that it needed to install drivers for a processor. Did it twice. Now device manager is showing 4 cores listed as "AMD engineering sample" and cpu-z shows it as a Phenom. Even overdrive shows 4 cores and i ran stability tests in overdrive for 4 cores and it went smoothly. Even windows tasks manager is showing 4 windows for cpu usage history.

Is the Kuma actually a phenom with 2 cores disabled by just the drivers? I'm scared to reboot it, fearing that Windows will lock the other 2 cores out. And tests in Sandra seem to confirm that there is actually 4 cores in there making calculations, judging by the benchmark results.

Is this possible? Just by windows installing drivers? Is there any way to forcibly make windows see the kuma as a 4 core proc instead of windows "accidentally" doing it like it just did to me?

I'm bumfuzzled and pleasantly surprised, all the while fearful that it will revert back to kuma status on the next reboot.

 

[masteryoda34]

Doubtful. Run cinebench single and multithreaded and check the multicore speedup.

 

[eternalone]

I always wondered if there was a way to enable the extra cores on the tri cores also. Investigate further u must, cuz that would be aweseome to buy a 75 dollar kuma and get a quad core with some tickering. Pipe dream maybe but still would be a cool value.

 

[masteryoda34]

My understanding was that the extra cores were physically fused off on the die.

 

[Idontcare]

Is it now prime95 stable? With the four cores magically enabled?

Cores are fused off if defective, not just for marketing reasons. Your CPU may very well have defective cores and having four of them showing as available to your OS might not be a good thing.

If it seems to good to be true...

 

[VirtualLarry]

That's pretty wild. Just like certain PIIs (Pentium IIs) showing the CPU serial number..
The only difference between a Pentium II and Pentium III at the time was fusings, and things like the CPU serial number were supposed to be disabled for the PII, but some of the chips slipped through with it enabled.

 

[dingleberrydorkbutt]

Originally posted by: Idontcare
Is it now prime95 stable? With the four cores magically enabled?

...

If it seems to good to be true...

Running prime95 right now and it shows 4 "workers"

I'll try to find cinebench and run it too.

 

[edplayer]

Originally posted by: VirtualLarry
The only difference between a Pentium II and Pentium III at the time was fusings, and ...

SSE?

 

[masteryoda34]

Can you post a CPU-Z screenshot also?

 

[dingleberrydorkbutt]

Originally posted by: masteryoda34
Can you post a CPU-Z screenshot also?

Running cinebench now.

Before I can do a screenshot, I'll have to install some sort of photo editing program or something. I don't have paint installed because I used a slipstreamed version of XP that I made that doesn't have paint and a lot of other stuff I never use. I'll see if I can download a free screenshot program somewhere

 

[VirtualLarry]

Lview pro?

 

[dingleberrydorkbutt]

got screenshots. Gonna sign up at photobucket and upload them. give me a few minutes.

Cinebench is saying a multiprocessor speedup of 3.82X

 

[dingleberrydorkbutt]

http://i225.photobucket.com/al...61/jpbrad/Screen02.jpg

http://i225.photobucket.com/al...61/jpbrad/Screen01.jpg

 

[SickBeast]

It says you got an Engineering Sample.

Where did you purchase the CPU?

 

[dingleberrydorkbutt]

newegg. Last week. Just built it today.

 

[dingleberrydorkbutt]

I was hoping this would be a quirk that would span all Kumas so everyone could enable 4 cores, but I'm just conjecturing.

Before I clocked it down to 2.9 and windows seen 2 more cores, cpu-z was identifying it correctly as a kuma 7750 with all the right info.

I'm scared to reboot it! :shocked:

 

[SickBeast]

Originally posted by: dingleberrydorkbutt
I was hoping this would be a quirk that would span all Kumas so everyone could enable 4 cores, but I'm just conjecturing.

Before I clocked it down to 2.9 and windows seen 2 more cores, cpu-z was identifying it correctly as a kuma 7750 with all the right info.

I'm scared to reboot it! :shocked:

It looks to me like you randomly received an Engineering Sample with all 4 cores enabled. Basically you're just lucky, and the odds of that happening are probably worse than winning the lottery.

:beer:

 

[dingleberrydorkbutt]

Originally posted by: Idontcare
Is it now prime95 stable? With the four cores magically enabled?

Cores are fused off if defective, not just for marketing reasons. Your CPU may very well have defective cores and having four of them showing as available to your OS might not be a good thing.

If it seems to good to be true...

You've got a good point, and I hope it's not the case. I've got it back on Prime95 and it's running stable whereas it would never run longer than a minute or 2 before the "transformation".

This incident could have repercussions all across the space-time continuum!

:laugh:

 

[SunnyD]

Kuma is indeed a Barcelona with 2 cores disabled. This would be a SERIOUS coup if there turns out to be some way of "enabling" the other two cores...

 

[dingleberrydorkbutt]

Originally posted by: SunnyD
Kuma is indeed a Barcelona with 2 cores disabled. This would be a SERIOUS coup if there turns out to be some way of "enabling" the other two cores...

That's what I was hoping for, not only for everyone else who bought one, but also if I ever have to re-install, how to make windows see the other 2 cores again. What is the trigger? It happened when I clocked it DOWN to 2.9.

 

[dingleberrydorkbutt]

I took a chance and rebooted it. It's still showing 4 cores. I'm as happy as a teenage girl at a Miley Cyrus concert.

 

[SickBeast]

Originally posted by: dingleberrydorkbutt
I took a chance and rebooted it. It's still showing 4 cores. I'm as happy as a teenage girl at a Miley Cyrus concert.

If you change the overclock, do you still have 4 cores? Maybe you found a magic unlocking frequency.

 

[SlowSpyder]

Originally posted by: dingleberrydorkbutt
I took a chance and rebooted it. It's still showing 4 cores. I'm as happy as a teenage girl at a Miley Cyrus concert.

Wow, 2.9GHz quad for $75. :thumbsup:

 

[nonameo]

Grats. It's probably worth more to collectors because it is an anomaly.

 

[Idontcare]

Originally posted by: dingleberrydorkbutt
I just assembled a new system based on a 7750 Kuma

OK the next question is are you certain they actually shipped you a Kuma? Or did someone in packaging (or the Newegg returns dept) screw-up and send you a Phenom when they were supposed to send you a Kuma?