Wednesday, December 02, 2009

Intel i5-750, Bad Chip Nixes Tests

I don't think these tests were representative; I think the chip is bad.

Below is the original article. I'll have to do a new one after I get the replacement chip.


I could not get the processor to pass an OCCT Linpack test at 2.9 Ghz. The problem is that the processor heats up quickly to over 72.7 C which is the chip limit. But, when you reduce voltage, the procesor becomes unstable. At 2.9 Ghz the processor gets errors with 1.16 volts. So I tried increasing to 1.18 volts VCORE and cutting the clock down to 2.8 Ghz. The processor is stable at 2.8 Ghz but heats to 75 C. Frankly, I could not get the processor to stay within range higher than 2.66 Ghz with Turbo turned off. I did some screen captures to show this.

The voltage indicated by OCCT on the following images will be slightly less since it drops during testing. When idle, the voltage shows correctly as 1.18 volts.

The maximum temperature for this processor is 72.7 C. With Turbo off, it just stays within the range.

However, with Turbo enabled the processor increases clock and heats up to 77 C which exceeds the maximum temperature. The thing that bothers me is that I'm seeing it exceed its thermal limits with the voltage set at 1.18. With the voltage at the normal 1.25 volts this would be even worse.

We now have our baseline. With the stock cooler, the i5-750 cannot be considered to be overclockable or even within limits with Turbo enabled. This means that the vast majority of people who buy systems with this processor have a marginal configuration at best. Intel pulled the same stunt with its original Kentsfield quads which were also out of range at stock speeds. Anand Lal Shimpi was well aware of this but in true overclocker fashion he simply averted his eyes and pretended it didn't exist. I had hoped the problem had been fixed with the G0 stepping and the lower voltage 45nm Penryns but now we have Nehalem and the problem is back.

There may be some Intel fanatics who will think I'm being unfair to Intel but I tested my X3 720 and PII 965 the same way. The X3 720 is fine with the stock cooler while the PII 965 needs improvement. However, it should be noted that the PII 965 in stock configuration is more than adequate and could even tolerate a mild overclock of maybe 100 or 200 Mhz. So, in stock configuration AMD does what it is supposed to while Intel fails. The next step is to bolt on the heftier Freezer 7 Pro cooler and see what happens.


muziqaz said...

nice info here :) keep it coming :)

David said...

2.9? haha - you don't know what you're doing.

By the way, these chips can perform well above 72*c, they will start to throttle down at 99-100*c. That being said, if you can keep it under 80*c you'll be fine.

I had the i5-750 @ 4.0ghz running 75*c with OCCT for a couple hours (granted on aftermarket cooler)

muziqaz said...

I can see idiots are coming out of the woods :) The Topic says Stock HSF.
David, who cares what you or anyone else can run for several hours on 3rd party cooler. This thread is about Stock cooler, which is not suitable for this cpu.
SuperFly, if you got kicked out from the zone, and you do not agree on scientia's interpretations, it does not mean, that you are everyone on the internet.

rge said...

The tj max for i5-750 is 100C. This corresponds to full load IHS max of ~72C. In other words from intels own formulas, at full TDP, there is a max gradient seen of 28C from tj to IHS.

At 72C core temp, you are still 28C away from tjunction max, so plenty of headroom, no where near thermal margin.

I noticed in your forum you state "such testing is badly needed after all the botched and non-existent testing from Anandtech and Toms Hardware Guide." Wow, if I were going to bash others, I would be humiliated to make such a novice mistake of clearly not knowing the difference between tjmax and IHS specs....especially when title is "thermally marginal". And apparently not knowing how to use OCCT either.

I have both amd and intel computers, could not care less about the test, but arent you a little embarrassed to be bashing others, when you clearly dont even understand the basics.

Ho Ho said...

Any chance you could post side-by-side CPU frequency charts in addition to these Linpack ones that supposedly show throttling?

Seeing exact same graphs for AMD would be quite revealing aswell I bet.

Scientia from AMDZone said...

As I said at AMDZone, I think you know what you are talking and I think the results don't match what the chip should be able to do.

I just did a new post showing the test results. I think it is clear that the chip is bad.